Why are you a Christian?
There are a few different ways you might answer that question. Depending on how you look at it, you might say that it’s because you accepted Christ or placed your faith in Him at some point. Or you might say that it’s because your parents nurtured you in the faith, so there’s never been a time that you did not believe in God and trust in Christ as your Savior. If you look at it from God’s perspective, you might say that it’s because He elected you to salvation before the foundation of the world and that you came to faith because of His sovereign work in your life.
But what if we ask the question differently: Why are you a Christian and not a Jew?
If you are like most Christians, you are a gentile, that is, not of Jewish descent or a convert from Judaism. Under the old covenant, gentiles had to become like Jews by marking themselves off from the surrounding nations—literally, in the case of circumcision, and figuratively, by abstaining from common pagan practices and worshiping the God of Israel alone.
In the Old Testament, it was expected that the nations would hear of the God of Israel and would come to worship Him. Israel was meant to be a blessing to the nations, who would then come to worship their God (Gen. 12:1–3). There are clear examples of gentiles converting or otherwise petitioning the God of Israel in Joshua 2, the book of Ruth, and 2 Kings 5; some other possible examples of gentile faith are found in Jonah 3 and Daniel 4 and 6.
The center of the old covenant religion was first the tabernacle and then the temple. At the dedication of the temple in 1 Kings 8, Solomon assumes that gentiles will come to worship the Lord there, and he asks that their prayers would be heard (vv. 41–43). Isaiah speaks of the nations’ coming to worship alongside Israel (Isa. 55), and the sons of Korah speak of the conversion of Israel’s enemies and their coming to the temple mount (Ps. 87). In the restoration after the Babylonian exile, the rebuilding of the temple meant that once again gentiles could come and entreat the God of heaven and earth (Hag. 2:7; Zech. 8:20–23).
In the early church, the relationship between the gentiles and the Jews was a bit of an open question. During His earthly ministry, Jesus spent most of His time among Jews, but He also interacted with gentiles and Samaritans (see Matt. 8:5–13; 15:21–28; John 4). There were many gentiles present in Jerusalem on the day of Pentecost (Acts 2), but the early church wasn’t sure what to make of gentiles at first. It seems to have been a pleasant surprise in Acts 10–11 that gentiles were granted repentance unto life alongside Jews (11:18). At the Jerusalem Council in Acts 15, the leaders of the church had to decide what was required of gentiles who placed their faith in Christ, concluding that they were not required to be circumcised. By not requiring of gentiles the entrance rite into Judaism, the church leaders were affirming that it is not necessary to become a Jew into order to be a Christian.
So, what is a Christian? A Christian is something else. He is not a Jew or a gentile. Paul addresses this new reality in Ephesians 2:11–22. In this letter, he is addressing a group of gentile Christians (v. 11), and he explains their relationship to God, to Christ, and to the Jews by using two metaphors. The first is spatial, and the second is architectural.