In 1859, Darwin's 'Origin of Species' was published. Everything which was written about the origin of man, and of life before that was wrong.
Nonetheless, people felt the need to explore these issues long before we knew the answer. And a great deal was thought about, discussed and written on the subject before this. People made up stories which explained the behavior they saw, and the world around them. Others tried to ease suffering by urging certain codes of behavior. Others tried to gain power through promoting certain codes of behavior. Most religions are a complex mixture of these.
Christianity has much in common with communism, in that they believe in the sharing of possessions. The main difference is that communists believe in using force to share other people's possessions where as genuine Christians (ie those who are not crypto-communists) would be reluctant to do this. Because they are so similar, they are incompatible, and communists and Christian leaders tend to argue very strongly that they are totally dissimilar.
Most religious people were until recently highly opposed to the theory of evolution because it undermined their own teachings, based on faith. Many religions now begrudgingly accept the truth of evolution, and are reverse engineering their teachings to minimize the contradictions.
Bureaucratized religions are also generally opposed to abortion. This is because they have instinctively known all along what Selfish Gene Theory has confirmed. Any religion which encourages abortion will eventually be bred out by a similar one which does not.
Likewise many religious groups are also opposed to genetic engineering and human cloning. This is because their beliefs (and therefore the power base of the leaders of those religions) relies on the principle of sanctity of human life. Scientific study of anything tends to demystify and objectivize it - and this will take away the 'sanctity' of it, and challenge the teachings and undermine the religious power bases.
The most useful thing about religion is that it gives clues to the human psyche. The explanations people invented to explain the unknown may have been wrong, but the fact that people invented these particular ones is revealing.
The most popular religions are
The first three rely on the notion of a single God, Christianity is based on the belief that Jesus Christ was specifically sent by God to preach his word. Islam is based around the teachings of a prophet called Mohammad (571-632).
Nearly all religions are about exerting control. Religion in its rawest sense is just an idea, but religions are living memes, and all ideas are continually threatened by other ideas. Religions which do not have survival mechanisms die. The survival mechanisms tend to involve control.
A religion which has one idea
Organized religions will not survive without controlling people.
Further, religions become bureaucratized or they die. With bureaucracy come power and corruption. Religious leaders find themselves in positions of power, and (being basically selfish), they abuse that power for their greater gain.
Someone's religion is their choice, and in principle none of anyone else's business, but the fact of the matter is that all organized religions are heavily based on control. Taking responsibility for another's immortal soul to enter the gates of heaven is just a around about way of asserting the right to control another's life.