Christians are called to love other Christians and non-Christians alike. There's a moral goal.
Non Christians have no goal. There are some/many who will be respectful and good, but there's nothing holding them to it. Over time, such a flimsly structure with no reasoning will fall.
If I had no reason to care for anyone else, I'd probably not care about anyone else. To a true atheist, there's no reason to care about anyone else. The outward cries of compassion would be for sheer virtue signaling and vanity. If there's no higher power or no morality.. and we're all just random beings.. giving to other and randomness would be foolish, which is what the world largely thought until Christianity taught the world charity. Most non-believers probably aren't aware of that, and even if they're taught, it hurts their narrative so they'll maliciously and willingly ignore it, so they can live another day as a keyboard warrior who hates Christians, as they do nothing for their community, pray for noone, and care for noone, while exaulting themselves in some mental masterabation practice.