And the father of circumcision - The father, that is, the ancestor, exemplar, or model of those who are circumcised, and who possess the same faith that he did. Not only the father of all believers Romans 4:11, but in a special sense the father of the Jewish people. In this, the apostle intimates that though all who believed would be saved as he was, yet the Jews had a special proprietorship in Abraham; they had special favors and privileges from the fact that he was their ancestor.
Not of the circumcision only - Who are not merely circumcised, but who possess his spirit and his faith. Mere circumcision would not avail; but circumcision connected with faith like his, showed that they were especially his descendants; see the note at Romans 2:25.
Who walk in the steps ... - Who imitate his example; who imbibe his spirit; who have his faith.
Being yet uncircumcised - Before he was circumcised. Compare Genesis 15:6, with Genesis 17.