I think a message specifically to non-religious voters would unfortunately turn off a lot of Christians. I know I roll my eyes whenever a candidate brings up prayer of how they’re siding with God, but I’ll still support the better candidate largely because I have no other option. I would even vote for a religious candidate whose policy goals align with mine over a non-religious candidate who has terrible positions, and I think that’s true for most atheists.

I don’t know how true the inverse is, but I suspect it doesn’t work for many people. Whether that’s because of the abundance of religious candidates or an ideological resistance to secularism, I’m not sure.