Salvation (the promise) is "sure !!!"

Romans 4:16;
Therefore it is of faith, that it might be by grace; to the end the promise might be sure to all the seed; not to that only which is of the law, but to that also which is of the faith of Abraham; who is the father of us all,
Romans 4:15-17;

De 32:47;
For it is not a vain thing for you; because it is your life: and through this thing ye shall prolong your days in the land, whither ye go over Jordan to possess it.

2 Corinthians 2:15;
For we are unto God a sweet savour of Christ, in them that are saved, and in them that perish:
2 Corinthians 2:14-16;