Here "kingdom of heaven" refers to God's rule as king. The phrase "kingdom of heaven" is used only in the book of Matthew. If possible, keep "heaven" in your translation. AT: "will live with God in heaven when he shows himself to be king" (See: [[rc://en/ta/man/translate/figs-metonymy]])
Jesus said "that day" knowing his hearers would understand he was referring to the day of judgment. You should include "the day of judgment" only if your readers would not understand otherwise. (See: [[rc://en/ta/man/translate/figs-explicit]])
# did we not prophesy ... drive out demons ... do many mighty deeds?
The people use a question to emphasize that they did these things. AT: "we prophesied ... we drove out demons ... we did many mighty deeds." (See: [[rc://en/ta/man/translate/figs-rquestion]])
Possible meanings are 1) "by your authority" or "by your power" or 2) "because we were doing what you wanted us to do" or 3) "because we asked you for the power to do it" (See: [[rc://en/ta/man/translate/figs-metonymy]])
This means the person does not belong to Jesus. AT: "You are not my follower" or "I have nothing to do with you" (See: [[rc://en/ta/man/translate/figs-idiom]])