Judaism, Christianity, Islam ... among others ... say there is only one God, and by the way, "it's a man."
Moreover, in the Judeo-Christian telling, God created a male first, and the female came out of the male, when just about everyone knows that females bear the young.
That God is a male is an uncritical belief held by many. It is not surprising this faith would appeal to males. What is surprising to some, is that this story is believed by women - that the All Mighty is a male.
Men justify their dominance of women and control of women's wombs based on these religious tracts.
It wasn't until the early 1800's that people figured out how the sperm worked in co-ordination with the egg. Prior to that, the "moment of conception" was not discussed in terms of sperm-and-egg. Prior to that, one of the prevailing views (adopted by religion) was that there were complete beings within the mother, and the act of sex caused one of the complete beings to gestate. Yes, sex caused the being to grow, but there was no "moment of conception" just because a man showed up.
The modern scientific understanding of impregnation came first, then a religious significance was attached to a scientific insight.
Nowhere in the Bible is the impregnation of an egg by a sperm mentioned, because this concept was not around until several thousand years after the Bible was first penned. Certainly, the idea that "life begins at conception" cannot be found in the Bible in the terms the anti-abortion forces mean it. In fact, during the Middle Ages, the Roman Catholic Church believed that a baby did not have a soul until three months after the birth!
The church is shifting ground in the details, but still maintaining the view that men are in charge of everything, including wombs.
As folks in South Dakota know, when a man places his seed into your womb, that's that. His seed must at all costs grow there ... his property ... and let no woman dare tamper with a man's property, even if afterward he has no interest in participating in the raising of the child.
That "life begins at conception" is, as I suggest above, a religious view and a recent one at that. What is troublous is that this doctrine is being forced on people who do not share this modern "faith."
Looking back at the story of Genesis, women play no part. It is when the man "does his thing," that life begins.
In short, life begins when a man says so.