Pray for them.
Prayer is like masturbation. If feels good, but it does nothing for the person you are thinking about.
Prayer is the exact opposite. Prayer leads you closer to God and the other is a sin and separates you from God's grace.
But if you want to be atheistic about it, then I'll ask you to provide evidence for your claims. God must necessarily be the First Cause of all, following the logic from Aquinas' 5 ways. Everything that is contingent must be brought about by something else. Since we can't have an infinite regress (otherwise nothing actually "is"), there must be something that comes before all. But the first cause must not be created, otherwise it is not the first cause. Therefore, the first cause must be Being Itself, non-contingent, infinite, the Unmoved-mover. That is what we call God.
And from there it makes sense that God cares about His creation. Prayer is the most effective way of achieving something because it does not rely on our imperfect abilities but on Him who is Perfection Itself.