There has actually been lengthy studies into the polytheistic practices of Israel. Where do you think all of the "golden idol" mythology comes from? Its meant to deter false idol worship. Even the very first commandments have to do with only worshipping one particular god (in this case, the god of whatever tribe was in power). If polytheism wasn't a problem then you wouldn't have to address the issue in such length. The polytheists origins of Israel are fairly well known in archeological circles; now of course they didn't remain polytheistic forever--by the time Christianity developed they were well known for their monotheism. My point was that initially, and in the seminal Biblical period (i.e. Exodus, etc.) they were a polytheistic people, and the fact that there are multiple names of God at different periods is one of the key indicators, because those names are also related to gods of Israels neighbours, which the Bible even explicitly states were polytheistic; religion didn't develop in a bubble--for instance when the Jews were brought into Babylon, they developed many of their most sacred rituals, such as circumcision; but circumcision isn't jewish--its Babylonian. The Jews just adopted it. There have been many studies and books written about the subject of the polytheitsic origins of Israel, but because it is contrary to the orthodox dogma it is usually ignored by most theists. Mark S. Smith has been one of the leading scholars on bringing this subject to the attention of the mainstream.

As to "what do atheists gain by rejecting god when they risk hell?"--that is an age-old argument known as Pascal's Wager. The basic refutation is "how do i know what is the right religion?" If i embrace Christianity then by the Muslim standard i am going to hell. If i embrace Islam then by the Christian standard i am going to hell. If i embrace Hinduism then by the Jewish standard i am going to hell. Theres no way out of this loop. But Pascal's Wager doesn't even need this refutation because the better one is simply "prove hell exists," or better yet "prove god exists," or better yet, "prove the specific god of INSERT RELIGION HERE exists."