Stubborn atheists won't convert even if you preach about the greatness of God. So I will look from their perspective.
Even IF Christ and the greatness of God were not real, and it was all a "Jewish lie". No matter how old the religion of Christianity is. It is a great motivator, a moral compass and a way of life. If you feel down and you feel unmotivated Christianity helps with a sense of meaning and power that science or the tree god cant give you. Think about how unjust and cold this world is, Christianity promises justice. Think about how meaningless this world is from a purely scientific perspective. A meaningless struggle for energy/life on a minuscule rock that floats in a bigger more meaningless world. But Christianity gives a reason for life and a way to live. The moral code of Christianity stands greatly today and still applies. Is against troonery/faggotry that is plaguing our current world, is against excessive materialism, lust and greed which are all things plaguing this world, and is against barbaric violence and hate that some other religions/beliefs have. And Christianity offers a great community, a kind and very giving community because those virtues are encouraged.
Even IF it was all fake, and after death, nothing happens. You get to live and die with a sense of meaning, having lived a righteous life, not being consumed by moral degeneracy and a sense of meaninglessness that le heccin peer-reviewed Darwin-backed scientific method or the tree god that just can't help.