I also believe God keeps His Word.
God's unilateral covenant with Israel remains in force, it's promises never fulfilled completely.
If you think Christ was not the final and all-sufficient sacrifice for our sins, then you’re not disagreeing with me, you’re disagreeing with Holy Scripture, the words of St Paul. Also, God didn’t revoke any covenant by providing his son as the sacrifice for the whole world, gentile and Jew alike. He favored everyone with his loving gift of himself.