I wonder if thinking about "free Will" is a partial solution to the question. I have taken a paragraph from Charles Hodge, Systematic Theology Vol.2. But to be fair, it is best to read all of Hodges' chapter on this point to come to your own conclusion.
Briefly, In Christ, the new man has a new character that can choose to do good. But since we carry about in us the dregs of sin still, we need God, (the Holy Spirit), to effect this new work in us. Does that make sense? Hope Hodge does if I don't.
Liberty and Ability.
"Confusion of thought and language, however, is not the principal evil which arises from
making liberty and ability identical. It necessarily brings us into conflict with the truth, and with the moral judgments of men. There are three truths of which every man is convinced from the very constitution of his nature. (1.) That he is a free agent. (2.) That none but free agents can be accountable for their character or conduct. (3.) That he does not possess ability to change his moral state by an act of the will. Now, if in order to express the fact of his inability, we say, that he is not a free agent, we contradict his consciousness; or, if he believe what we say, we destroy his sense of responsibility. Or it we tell him that because he is a free agent, he has power to change his heart at will, we again bring ourselves into conflict with his convictions. He knows he is a free agent, and yet he knows that he has not the power to make himself holy. Free agency is the power to decide according to our character; ability is the power to change our character by a volition. The former, the Bible and consciousness affirm belongs to man in every condition of his being. The latter, the Bible and consciousness teach with equal explicitness does not belong to fallen man. The two things, therefore, ought not to be confounded".