Religion is a moral necessity for an inherently bad people. Even the most fundamentalist Christians defend their view by saying that if you do good in your life and devote yourself unwaveringly to God, or Jesus, or whoever, you will be rewarded with heaven in the afterlife. It is the single most powerful (and ultimately only) drawing feature to Christianity—if you are a Christian, you will be rewarded either here or in the afterlife, and usually (to some degree) both. The only disagreements lie in how Christian you have to be to qualify.
A fundamentalist atheist is far more dogmatic, and far more extremist. If you do evil, there will be no punishment. If you help no one, there will be no hell. And yet, it is expected that you do good in this world. Many of the most devoted environmentalists are atheists. The founders of modern democracy professed a nonbelief in God. Many of the most universally charitable organizations are secular or humanist: Red Cross, United Way, Peace Corps, etc. while religiously motivated groups like Boy Scouts of America, The Catholic Church, and Rescue Missions at the very least require a show of fealty of their benefactors, and at worst will flatly refuse to help people in need who are outside of their religious circle.
And in exchange for their good deeds, the atheist gets nothing. No heaven, no afterlife, no golden camels. There isn’t even a mythology among atheists where anyone has been rewarded for their good deeds. On the contrary—if someone is rewarded, the ‘goodness’ of their deeds is thrown in doubt (such as happened to the Presidents of secular charity United Way on several occasions). So what you have is a group of people who are expected to sacrifice themselves to the benefit of others, to the benefit of the Earth, and even to the benefit of generations that don’t even exist yet, and they are expected to do so without any congratulations, any rewards, and any fringe benefits of any kind. But they have to do it anyway. Now that’s a true test of faith.