Many of the most well known atheists have given their reasons for wanting to change people's minds about religion. Some point out the damage that religion does, others demonstrate how seeing reality as it exists helps you in the long run. I agree with both of these views. I think that religion has caused some atrocities and given other people cover for their immoral actions. I also think that viewing reality, while not always pleasant, is very beneficial. But none of these reasons are my reasons for trying to demonstrate the truth about the atheist perspective. I want you to see the truth because I care about you.
My reasons might sound strange to people if their faith is extremely important to them. It might seem like I am actually trying to hurt them instead of help them. After all, it might appear like I am trying to take something from them and leave them impoverished for the loss. But that isn't the case. I want them to see reality for all its glory. I want them to see what their fear and blind faith is costing them. I want to show them that there is no reason to fear eternal torture in the pit of Hell, or be concerned about the judgment of a being that doesn't exist. Every moment of their lives spent worrying about these things is a moment that they don't get to enjoy the wonders of reality. And since, unfortunately, all our time is limited, every moment that we waste on worry and fear is a moment that neither we, nor anyone else, will benefit from.
But since I want to help people live better lives, why don't I spend more effort talking to all of the Christians? I live in the bible belt, so I am surrounded by Christians. If people could wear their beliefs in a visible way, I might be able to go days without seeing anyone that wasn't a Christian. The reason that I don't discuss my feelings with these Christians is because most of them already live as if they were atheists.
Given what most people seem to use the word Christianity to mean good person, I suspect most people will have a difficult time believing me when I say that they are already living like atheists, but it's true. They don't waste one day a week going to church in some misguided attempt to keep an angry god placated. Any money they give is given to people and organizations that they care about instead of paying for a building and hiring someone to mislead them. Their opinions are formed from thinking and interacting with other people instead of trying to reinterpret ancient folktales to imbue them with modern meaning or beseeching someone to interpret those tales for them. They have discarded so much of the ancient beliefs and superstitions that what remains could come from any moral philosophy regardless of its origin. In short, they are just good people doing their best to live and help other people do the same. And they do all this because they are good people, not because they are afraid of an entity that they have never interacted with outside of a storybook.
They walk like atheists, talk like atheists, act like atheists, and call themselves... Christians. But I've never cared about what they call themselves. They are already not loosing any part of their lives to ancient beliefs and superstitions. Their lives are already their own. And for those people whose lives aren't their own, I will still be here trying to help them see reality and salvage what is left of their life.