Assuming nihilism or More than anyone else selfishness on materialists is no less inappropriate than surmising Christian morals as 'treat this life as a weigh station for the next life, feign altruism for the sake of avoiding death, spread a message based on fear of mortality and the belief that without a security camera in the sky you would be a raving lunatic with no virtues or meta-ethics.' It's an innately insulting argument, and not actually representative.
The only rational basis for any kind of moral reasoning in the godless husk universe that materialists accept is self-interest. It may well indeed please you to be a good person and it may very well be socially advantageous as no one likes jerks. But in the end of the day there's no more value to your life than that of an amoeba's. (No matter how much you may personally value it). There's certainly no justice. Stalin and Hitler never really answered for the collective millions they murdered. (Hitler suffered a second of pain before going to the oblivion that awaits everyone anyway). You offer nothing but moral subjectivism because assuming materialism that's all there can ultimately be. It's nihilism whether you call it that or not.
Neither is the idea that afterlife belief is necessary to have purpose, compassion, empathy, charity, commitment, resolve, morals and ethics.
It's not necessary, just baseless beyond self-interest. And when it's in your self-interest to play hard and loose with those things there's certainly no answering for it. (Assuming you don't get caught). And yes of course, Christians can play loose with morality as well. But when I do something bad I believe I will reap that bad for eternity. This life (fellow traveler) determines the disposition you will carry, consciously, forever. There's nothing more serious and more meaningful than this life, because it's our one chance to decide what side of the cosmic moral order we align ourselves with. With materialism, your only hope is in the best this world can offer, which is always subject to impermanence and dissatisfaction.
And some of the most shining examples of nations with these in spades are secular countries with high non-belief (re: Scandanavia, Japan, etc.)
They're also technologically advanced and rich. It's easy to reject hope beyond this world when you are relatively comfortable in this world. Basically, I don't buy that the adverage Swede is a beacon of virtue.
Like, you know...heaven belief. Where the majority of people are killed (sorry, 'they bring it on themselves') and a select few who have their being fundamentally altered do so after entirely devoting themselves to a position of tyranny. (But it's wholly good, we promise.)
I'm not even seeing a coherent point here. The last century is a testament to the horror brought by those who sought to replace God with the state. Everyone worships something; be it God, sex, money, race or the idea of an all-encompassing, ideological and re-distributive state. I personally, choose God. And the hope of something better beyond this short, fragile life.