Let (R) be the denial of moral defeatism. I’m worried about the truth of (R) quite apart from God’s existence, so assume the possible moral responses in (R) do not include divine responses.
R. For any evil E that occurs, there is a possible response R to E such that R is a free moral response to E, R is impossible in the absence of E, the moral value of (R & E) is (neutral or) positive.
I include of course any evil E that is occurring, has occurred or will occur. The denial of (R) is the position that there exists some evil to which every possible moral response is defeated. That is, every possible moral response is such that (R & E) is negative. By free moral responses to evil I have in mind actions (individual and collective) that display moral courage, charity, perseverance, compassion, care, hope, mercy, generosity, justice and the like. Some well-known exemplars of free moral responsiveness include M. Gandhi, M. L. King, Mother Teresa, among, of course, many others. These individuals display what is possible in the way of free moral responses to evil. Now consider (P1) and (P2).
P1. If moral defeatism is false, then the existence of gratuitous evil depends largely on what we freely choose to do.
P2. If moral defeatism is true, then there is (was, will be) some evil E such that there is nothing anyone (or any group) could ever do, over any amount of time, in response to E that is not defeated by E.