But this is not always so?

No. For as the Lord reserves for Himself the freedom to show mercy to the children of the ungodly, so on the other hand He retains the power to elect or reject in the generation of the faithful as it seems good to Him (Rom 9:15-22). However, He does this in such a way that men may acknowledge that this promise is not vain or fallacious (Rom 2:6-10).