You keep saying salvation is by grace. What do you mean by that?

Grace is God showing favor to those who don't deserve it, but who, in fact, deserve the very opposite. It is closely linked with the idea of a gift. You do not earn a gift. That would be wages. You receive a gift and say "thank you." Grace and works cannot be mixed. It has to be one or the other. Grace must be distinguished from justice. In justice, you get what you deserve. In grace you get favor that you don't deserve.