Sometimes, Scriptures mean different things depending on the point of veiw. Its important to read the text with the surrounding verses to really understand what the writer is saying. (
Rom. 11: 26-29)
"Repentance" can mean that once a gift and calling is given, it is never revoked. A man is called to preach, submits to that call, and at some later date, backslides. While he may not be preaching, the desire, the call to preach is still with him. So, his gift, his call, remains with him, even though he is in a backslide condition.
Rom 11:29 For the gifts and calling of God [are] without "revocation".
"Repentance" can also mean "regret".
Rom 11:29 For the gifts and calling of God [are] without "regret". Once we are called to follow Christ, we should never regret our decision to do so.
There are two groups of people being discussed here: 1. The Jews, followers of the Law of Moses, who Paul refers to as "enemies for your sake". This would be to say "your enemies". They were, at this writing, actively persecuting the other group: The NT Church. 2) The "election" refers to those who were "called out" of Judaism, and who were now following Christ. The church. The church was being persecuted by the Jews. The Jews regarded themselves as enemies of the church- but Paul admonished the Christians to regard the Jews as "the beloved" - God's chosen, yet rebellious people. He said to regard them as the "beloved" out of respect of "the fathers". (i.e, The Patiarchs). So Paul is telling the Roman Christians who were being persecuted to never regret their service to the Lord, even though they were being persecuted for their faith.