Why would such a vast number of people participate in such a huge delusion? It seems incredible the human race can be so gullable.
Hi pelican,
The simple answer is that the human race grew up in a world full of frightening and inexplicable phenomena. They weren't able to get to the true explanations. They knew nothing abut meteorology, so, when they heard thunder, they ascribed it to the thunder god. Imagining that thunder was the anger of an intelligent agent seemed simple and believable to them. Humans are apt to anthropomorphise natural phenomena, especially puzzling ones, so this was an appealing idea, which allowed them to feel that they understood the world around them.
Later, as these superstitions developed, they became enmeshed with traditions and stories and were handed down the generations. They became more sophisticated and complex and gradual evolved from primitive animism to polytheism, to monotheism.
Of course, today we have a wealth of real explanations for natural phenomena, so it is tempting to conclude that the next steps in this process are agnosticism and, ultimately, atheism.
The probability of God's existence cannot be decided by an appeal to popularity. It doesn't matter how many people believe in an idea, it can still be wrong. In actual fact, there are many different varieties of theist around and they mostly disagree with each other, so an appeal to popularity is especially useless in this case.
Wiki writes:
When it came to power in 1933 the Nazi Party had over 2 million members. Once in power, it attracted many more members and by the time of its dissolution it had 8.5 million members.
No-one ever says "Well, 8.5 million Nazis can't be wrong, can they?". People don't say this for a reason. They can be wrong and they were wrong. The popularity of an idea is no guide to its veracity.
Mutate and Survive