A.T. Robertson Commentary Galatians 2:20

"I have been crucified with Christ; and it is no longer I that live, but Christ living in me: and that [life] which I now live in the flesh I live in faith, [the faith] which is in the Son of God, who loved me, and gave himself up for me." — Galatians 2:20 (ASV)

I have been crucified with Christ (Χριστω συνεσταυρωμα). One of Paul's greatest mystical sayings. Perfect passive indicative of συσταυροω with the associative instrumental case (Χριστω). Paul uses the same word in Ro 6:6 for the same idea. In the Gospels it occurs of literal crucifixion about the robbers and Christ (Matthew 27:44; John 19:32). Paul died to the law and was crucified with Christ. He uses often the idea of dying with Christ (Galatians 5:24; Galatians 6:14; Romans 6:8; Colossians 2:20) and burial with Christ also (Romans 6:4; Colossians 2:12).

No longer I (ουκετ εγω). So complete has become Paul's identification with Christ that his separate personality is merged into that of Christ. This language helps one to understand the victorious cry in Ro 7:25. It is the union of the vine and the branch (John 15:1–6).

Which is in the Son of God (τη του υιου του θεου). The objective genitive, not the faith of the Son of God.

For me (υπερ εμου). Paul has the closest personal feeling toward Christ. "He appropriates to himself, as Chrysostom observes, the love which belongs equally to the whole world. For Christ is indeed the personal friend of each man individually" (Lightfoot).