Well, I don't think someone can legitimately call themselves a Christian or Muslim if they don't believe in a god. They can live by the moral codes laid down by those religions, but without belief in a god it's really not Christianity, Judaism, or Islam.About all religions can be used as philosophies - it's not like Islam, Judaism and Christianity have nothing left if you take away the supernatural parts. A christian, jew or muslim can choose to believe in that religion's moral code and rules without believing in God and miracles in just the same way as a buddhist can choose not to believe in a soul, rebirth and other supernatural phenomenons.
