Few moments can feel quite so alarming as late at night and on unfamiliar roads, when you realize your car is almost out of fuel. Will there be somewhere to fill up nearby? Will the place be open? Your eyes are fixed on the fuel gauge. With heart thumping and palms sweating as the miles go by, you envision your car sucking up the last drops and fumes from the tank before sputtering to a halt, leaving you stranded.

For too many of us, our experience of the Christian life and ministry feels similarly precarious. The fuel light is flashing; very little seems to be left in the tank.

All too often, however, we’re running on empty because our view of God is empty. Amid life’s trials and exigencies, our view of God has slowly shrunk and become distorted and skewed, such that we do not set out filled with joy and satisfaction in him. We may feel that our ministries are vital and that God is relying on our courage, faithfulness, and brilliance: a burden we can’t really bear. We begin to imagine that God needs us and leans on us unfairly. We begin to imagine him as a demanding taskmaster and quietly resent his calling.

“All too often, we’re running on empty because our view of God is empty.”

In all our efforts to serve Christ dutifully, we may not truly enjoy our all-generous, giving God, but instead run on the fumes of our own devotion and spiritual energy. And if our God is not full, neither will we be. Only a renewed vision of God’s glorious fullness will help us. So where might we look for fresh vision?

How to Take Heart

Jesus knew his disciples would run out of gas. “In the world you will have tribulation. But take heart; I have overcome the world” (John 16:33). As he prepared to leave this world, he knew that they, as his holy people in a hostile world, would face trouble, hardships, discouragements, and persecutions. And he wanted them to know something when they did: he had already overpowered the fleeting darkness of this passing age. So, he tells them, take heart.

Yes, but how?

In every Christian’s life, we have tribulations that, of themselves, might easily cause us to lose heart. Family life eked out in the shadow of depression and anxiety. Local church ministry in what seems like a spiritual desert, painfully low on encouragements and visible fruit. A calling to overseas missions attended by loneliness, isolation, and homesickness. How can we, day by day, in the pressure and pain, find perspective, peace, and joy?

When Jesus said he had overcome the world, it was the conclusion to a longer discussion. “I have said these things to you, that in me you may have peace” (John 16:33). When the world is trying, our spiritual energy is drying up, and we wonder if we can go on, we need to plug ourselves into the darkness-conquering words of Jesus. These things are the key to taking heart and persevering.

Sustained by His Fullness

In John 16, Jesus tells his disciples that, after his crucifixion, resurrection, and ascension into heaven, the disciples will have the privilege of direct approach to God in heaven in his name when they pray (John 16:26). With the Lord’s ascension and the coming of the Holy Spirit, the endless resources of heaven will be at their disposal to ask whatever they need (John 16:23). So, says Jesus, “no one will take your joy from you” (John 16:22), and “your joy may be full” (John 16:24).

In Christ, the superabundant Father of glory is our own Father, lovingly attending to our needs and requests. And he has joy to spare for struggling saints. In the challenges and troubles of our lives today, this is the vital source of overcoming joy and peace: our God is full and loves to fill us.

God revealed himself to Moses as “I AM”: “the One Who Is.” Unlike us, who are born and named, God does not receive his name, identity, or existence from anyone or anything else: his life is self-contained and self-sustaining. As Paul tells the Athenians,

The God who made the world and everything in it, being Lord of heaven and earth, does not live in temples made by man, nor is he served by human hands, as though he needed anything. (Acts 17:24–25)

Far from needing anything, our God is the very definition of fullness. God alone is gloriously, completely, independently himself.

Sustained by His Filling

Yet the life of God is not a fortress, shut up against the world. God’s satisfied self-existence does not mean grand isolation, vacuum-packed and hidden away. No, the very life of God — all that he is in himself — overflows and is the source of our happiness as well as his own.

Jonathan Edwards imagined God in this eternity and wrote, “God undoubtedly infinitely loves and delights in himself. . . . The infinite happiness of the Father consists in the enjoyment of his Son” (The Works of Jonathan Edwards, 21:117). In other words, God’s full and happy life is triune. The Father has eternally loved his Son (John 17:24). The “infinite delight” of God, Edwards says, is “in the Father and the Son loving and delighting in one another” (The Works of Jonathan Edwards, 21:118).

“Here is a God who, even before, beyond, and above all created things, exists in loving and delighted fellowship.”

Here is a God who, even before, beyond, and above all created things, exists in loving and delighted fellowship. Here is a God for whom a creation makes sense: an opportunity “to communicate and spread his goodness,” as Richard Sibbes put it (The Works of Richard Sibbes, 6:113). Here is a God who would not condemn rebels and sinners to perish without first giving his one and only Son in measureless love for the world (John 3:16). To this God, Jesus now assures his friends, they may go in all their need and weakness.

Sustained by His Sacrifice

Jesus spoke his promise that he has overcome the world just hours before he went to his death. His timing is perfect, because the cross at once exposes the sin and emptiness in us and reveals the fullness of God: the cross is the key to our overcoming.

While we are often tempted to pursue our callings in our own strength (and risk burnout and bitterness in the process), the cross exposes us as helpless sinners who can offer nothing to God. It shows us what we deserve as all our ways are condemned in the flesh of Christ (Romans 8:3). At the cross, we are relieved of the illusion that the purposes of God rely on us.

And the cross relieves us of the illusion that God is demanding and cruel. Our Father has not withheld from us his own Son and will not hold out on us for anything else (Romans 8:32). His death is the seed of our eternal life and the promise of our resurrection. At the foot of the cross, we are humbled again and again and shown our own natural emptiness, yet there we also fill our gaze afresh with the glorious self-giving of God in Christ.

Unexhausted Fullness

Nowhere is God’s heart on display in brighter colors than on the cross of Christ. God is so full of life that he lays his own down for his enemies. God is so full of love that he pours it out on the unlovely. God is so good that even the darkest night of death will turn to bright morning.

If we want to last — in life, in marriage, in parenting, in ministry — we need a vision of God that is not only big enough, but good enough. A grand and majestic God could intimidate or scare us; his hard callings might appear harsh and unkind to us. But the Father of our Lord Jesus Christ is eternally good and giving. From his fullness we have all received, grace upon grace. And if you draw strength from his fullness, you will, as John Howe writes in his treatise on delighting in God, “still find a continual spring, unexhausted fullness, a fountain never to be drawn dry” (83).

Who is God? What is he like, and how do we come to know him? What is salvation?

We may be tempted to consign these questions to the first weeks of evangelistic courses or the earliest years of discipleship, yet they were central to the ministry of Cyril of Alexandria (c. AD 376–444). As a bishop and theologian with far-reaching influence, he saw the gravity of these questions, as well as the pastoral fallout if Christians thoughtlessly rattled off pat answers.

Cyril’s heart was that believers would consciously and joyfully place Jesus Christ front and center in their understanding of God and their salvation. His tenacious Christ-centeredness shaped some of the most significant all-church councils and creeds that we have inherited today.

Seeds of Scandal

In the fifth century, perhaps the most famous church in the world was the Great Church of Constantinople. Enthroned there in the heart of the “New Rome,” its archbishop carried a leading political and theological voice. In 428, the job was given to a well-loved Syrian preacher named Nestorius.

Nestorius wanted to stop all references to Mary as theotokos, Greek for “Mother of God.” The title had long been popular and had tried to express something of the wonder of the incarnation: that a human mother should give birth to God the Son in human flesh. In Nestorius’s mind, however, the title was imprecise and dangerous. His concern was not that it encouraged undue veneration of Mary (that would develop later in church history), but that it implied something about God that he could not accept.

That God should be born, naked and crying, depending on a mother to feed and wash him, was unthinkable. God, eternally unchanging and untouchable, simply could not be straightforwardly identified with the wriggling baby in the manger. No, Mary must be called “Mother of Christ,” not “Mother of God.” There had to be a clear distinction between the two. Nestorius devoted a sermon series to the subject, and his troubled colleagues began to ask, If Mary is not the “Mother of God,” then just who is her son?

Nearly seven hundred miles to the south in Egypt, Cyril, the archbishop of Alexandria, was alerted to the emerging scandal. Having spent years writing biblical commentaries and theological works on the Trinity, he knew he had to step in and challenge Nestorius. Like the apostle Paul centuries before, Cyril saw that when the identity of Jesus Christ is distorted, so is our understanding of God and what it means to know him — with devastating consequences. “Another Jesus” goes hand in hand with “another gospel” (2 Corinthians 11:4).

Another Jesus

Nestorius believed in Jesus as the eternal Son and Word of God. He believed, along with the Council of Nicaea of AD 325, in the humanity and divinity of Christ. Yet the distortion of Jesus he presented threatened to undo the orthodox faith he claimed to hold.

“‘Another Jesus’ goes hand in hand with ‘another gospel.’”

Nestorius’s deepest problem was that he had his definition of God prepared long before he came to look at the person of Jesus Christ. The carpenter from Nazareth, in the manger and on the cross, could not fit with his understanding of God. Following his mentor, Theodore of Mopsuestia (c. 350–428), Nestorius taught that Mary’s son was a separate man from God the Son: a man assumed (taken up) and brought into fellowship with God. Jesus and the Word enjoyed a relationship of unique cooperation, with the Word graciously sharing the honor of his sonship with Jesus. Because of his obedience, Jesus came to earn his resurrection into a new life free from death and decay (Nestorius, Bazaar of Heracleides, 1.3).

For Nestorius, although the people of first-century Israel saw an individual human being with divine power, they were actually looking at a kind of partnership of two sons, presented in one man. A glass wall ran down the middle of Jesus Christ, shielding the eternal Word from the human experiences and troubles of the man until he was perfected. While Nestorius was happy to worship and adore the man Jesus, he did so only beside “the one who bears him” (Sermon 9.262).

Cyril could see that Nestorius’s Jesus was only a man like the rest of us, elevated to a special relationship with God. The one who suffered and died on the cross was not technically God the Son himself coming to us in the flesh. Instead, God wore gloves, as it were, to deal with sinful humanity. He promoted a man to divine dignity, setting before us a supercharged example of holiness to imitate. Nestorius’s Jesus is the perfect Savior for those who would win salvation for themselves.

The Real Jesus

In AD 431, at the Council of Ephesus, Cyril (along with most of the other bishops) opposed Nestorius’s teaching. They saw that it contradicted not only the biblical Jesus but also the biblical gospel. Leaning heavily on Cyril’s writings, the fathers of the church affirmed that while there are two natures in Christ, there is only one person.

In other words, God the Son was the person in action during the incarnation, whether he was walking on water by the Spirit or tired after a journey in his flesh. He maintained his unchanged, eternal divine nature, but had added to himself a truly human nature — along with all of its capacity to fall asleep in a boat, battle temptation, or suffer crucifixion.

“The Son of Mary was none other than God the Son himself, made known and living in human nature as well as divine.”

God the Son personally took all that we are to himself, choosing this way of being “for us and for our salvation,” as the old Nicene Creed had it. In answer to the question of the pastors of Constantinople, the leaders gathered at Ephesus were clear: the son of Mary was none other than God the Son himself, made known and living as man as well as divine.

Cyril’s Influence

In time, this picture of Christ came to be known as the “hypostatic union”: a true union of divine and human in the one person (Greek hypostasis) of God the Word. It was not an agreement between two parties with separate agendas, nor a cooperation of equals.

In fact, there was a critical asymmetry to this union, for the humanity of Jesus comprised no separate person, as Nestorius had taught, but was “personated” by the Son. Humanity had been added to a preexisting divine person. There was no Jesus to know other than the second Person of the Trinity, now made flesh. This meant that all of Jesus’s actions and words were truly the actions and words of God the Son.

Just as it was right to call Mary theotokos, so it was right to say that God the Son played in the streets of Nazareth as a child, that God the Son had compassion on lost and helpless sinners (Mark 6:34), that God the Son shed his blood on the cross for our redemption (Acts 20:28). For it was no other person, no other human, but only the eternal Word in his humanity. After all, he was Immanuel, God with us.

These biblical convictions were honed and clarified by another all-church council held in Chalcedon in AD 451. Responding to another stream of false teaching, the church again turned to Cyril’s Christology (though he had now been dead some seven years). The gathered bishops affirmed that the one person of Jesus Christ was to be acknowledged in two “unconfused, unchangeable, indivisible, inseparable” natures. They confessed that the divine and the human in no way undermined or undid one another, yet that he was nevertheless just one person: “one and the same Son” who was with the Father before all things and who was born of Mary for us and our salvation. Chalcedon rang deeply with the echo of Cyril’s theology.

God Was Pleased

Nestorius’s precooked doctrine of God meant that he struggled to get divinity and humanity in the same person. There was an unbridgeable gulf between the divine and human, and his theology left believers the task of crossing it on their own, following at a distance in the footsteps of a superman from Nazareth.

Cyril, however, began with Jesus and allowed the Son of God to reveal the nature of God (John 1:18). And the God revealed in Jesus, he saw, was pleased to draw near to sinful humanity in person (Colossians 1:19¬–20). He came in uncompromised deity, but with mind-bending condescension, to cross the divide himself. The Son stepped in, clothed in our humanity, laying down his life, and taking hold of us when we could not save ourselves. In Jesus, God truly demonstrates his love for undeserving sinners, up close and personal.