What does Paul mean by 'faith in Christ' in Galatians 3:26?
Paul means the finished work of redemption: Christ's death, burial, shed blood, and resurrection. Faith in Christ, not baptism into a denomination, makes believers—largely Gentiles—children of God. Paul continually stresses the power of Christ's resurrection as the object and assurance of that faith.
Les explains that Paul is writing in Galatians 3:26 to Galatian believers, mostly Gentiles: “you are all the children of God, by faith in Christ Jesus.” When Paul speaks of faith in Christ, Les says he is speaking of the whole finished work of redemption—His death, His burial, His shed blood, and His resurrection. Paul stresses constantly the power of His resurrection. Then verse 27 speaks of being baptized into Christ, not into a denomination; Les emphasizes there is not a drop of water in that verse. He compares this to Romans 6:3, where a guest preacher said there is no water, and Les now sees he was 100% right.
For ye are all the children of God by faith in Christ Jesus.