There are states outlawing atheists from holding state offices, but the oath of office for US president does not contain religious references. It is specified

There are states outlawing atheists from holding state offices, but the oath of office for US president does not contain religious references. It is specified in the Constitution. Oaths of office for other federal positions do contain the phrase "so help me God," but so far as I know there has never been a problem omitting it; I had several friends in Federal service do so.