Ironic post is ironic. Sola fidelis is inherently a religious, and not an ethical or moral, concept. Yet, ethics and morality are focused on the good. Thus, one could, in theory, be good and yet not ask God to save their soul (in fact, if they were always good, why would they need to ask God to save their soul); yet, you would state that this person is excluded from heaven because they have not placed faith in God. However, to place faith in God is to act religiously. Yet, you assert that religion will get you nowhere but hell. Quite a predicament.
This is the wrong response and challenge to give to Bamacheats. I would suggest using the understanding of the trinity (God the Creator, God the judge, and God the spirit), and assert that Abraham did believe in the tripartite God of the Christians. According to the story, Abraham certainly believed that God created; he was spoken to through the spirit; and, in willingly going to sacrifice Isaac, he must have believed that God would judge him. The fact that he does not use the term "Jesus" is of no consequence.