Allow me to start answering this question with a question: why should atheists really care about their arguments? We are living in a free world in 21st century, Spanish Inquisition spies are not lurking from the dark. So, let's see these words written in gold: "To each his own".
Nobody is owing an explanation to anybody else what they choose to believe. The last time I checked, people had their heads for better purpose than just for wearing hats, so which human being feels called upon to impose or preach to another human being his own beliefs or a lack of them? Don't we all have our brains to think for ourselves?
If you want to believe in God, you have my blessing. And the same blessing goes to all those who couldn't care less if there is a universal intelligence orchestrating this global soap opera that we are proudly calling "civilization".
If your question was "what religious people believe", I wouldn't even bother answering, because they have their right to share their belief with the world. But you asked "why should one stop being an atheist?" Of course, again, you have a right to ask what you want, but then we have something like the issue of normative nature on hands.
No one is setting the norms. No one, no matter how much they fancy that they are backed up by a "being" who gives them some authority. We have enough our politicians to play authorities to us (even though they should be serving us), and media to mess with our minds - we don't have to do it to one another. We should all stick together against anybody who is violating our basic human dignity, our freedom to think, feel, and believe what we choose.
To my understanding, someone telling me what I "should" believe or not, is like telling me what I should, or shouldn't have for my dinner today. It's sickening what I am reading from some participants in these religious discussions, when some of them call others "Hypocrites", "Satans", "Fools". Where is that "unconditional love" they are propagating? Where is that "tolerance", and all other slogans which should make them "better" people than non-believers?
Isn't God supposed to be pure love, or is it a word that we mix with our saliva before we spit on others? Come on, folks, LET'S START LOVING for a change! Let's allow some freedom to others, maybe that would free us too!