People aren't suicidal because of their set of beliefs or because of the group to which they belong, they are only suicidal because of their circumstances and those do change between groups. Obviously the religious community is, and unfortunately so, the closer community out of theist and atheist. I don't understand how this statistic is an argument for religion though, confounding stuff indeed.
Religion is an attempt to answer the philosophical questions of the unphilosophical man.