If you look around you, you will see that there are plenty of people with genuine interest, aptitude and talent for sciences. Not everyone you meet might be equally gifted in sciences, but everyone of us knows someone who is really talented at engineering or medicine or pure sciences.

Thousands of years ago when all of these religious texts were being written, people back then were just like us. There were people who were genuinely talented at sciences and had aptitude for it, even in those days.

Now of course, back in those days there were no universities where you can get a B.Tech degree in chemical engineering if you were really interested in chemistry. Or an MBBS degree if you were interested in human anatomy. You could either become a priest, a warrior, a king, a farmer, a merchant etc. If you wanted to conduct scientific experiments and learn sciences, your parents would beat you with a stick and force you to take up their occupation. If your father is a farmer, he would force you into farming. If your father is a priest, he will force you to become a priest. Even if you rebel against your parents, the society will kick your ass and force you to do what your parents were doing.

Now just because you became a priest you are not going to let go of your passion for sciences right? You will still conduct scientific experiments in your free time. Try to measure the distance between the Earth and the sun or try to find the diameter of the planet or something along those lines.

Now what do you do once you find the circumference of Earth? You cannot go tell your farmer friends about it, they will laugh at you. They will tell you, you are an idiot for thinking earth is round, let alone calculating it's circumference.

So what do you do instead? Tell them that you were praying all night long and god came in your dream and told you that the earth is a sphere and the circumference of the planet is 40,000 kilometers. So you did some experiments to verify this and you found that the circumference of the planet is actually 40,189 kilometers which is very close to what god told me! That's it! Now all your farmer friends start believing that you have a direct connection to god.

As you are a priest you are in charge of all the religious scriptures. You write all of your scientific discoveries in these scriptures and these get passed down from one generation to the other.

But now the problem is, that there are other people who see what you have done and those other people will start doing the same thing as you. Whatever non-scientific bullshit they believe is right that they may or may not have verified, they will enter it into the religious scriptures too. If some body questions them, they will just say that god came in their dreams and told them cutting your hair after sunset is bad. Well in actuality, the reason this person wrote that is because their annoying as fuck neighbor keeps cutting hair after sunset and leaves his hair on the road or something.

Of course this is a very harmless example. But there could be something extremely vile that also gets added to the religious scriptures the same way. You don't like homosexual people, you just say god told you that you cannot be homosexual. You don't like alcohol? You can write it up in the scriptures that alcohol is bad and now several centuries down the line, no one is allowed to drink alcohol. Period.

Now this stupidity doesn't end with one generation. Thousands of years after these scriptures were written, people will still keep translating these scriptures into modern languages and keep preserving them. People will read these scriptures and see that it claims that the circumference of earth is 40,189 kms. We have used advanced scientific instruments, satellites and computers to calculate the circumference of earth and it is 40,069.88789298 kms! Which is extremely close to what the scriptures claim. And these books were written 1000s of years ago, when people did not have computers! But do you actually need computers to find the circumference of our planet? Nooooo. It just needs basic common sense. But people don't know that. People think that god legitimately told these people in their dreams the circumference of our planet.

Now once you have verified one piece of information in these scriptures, you actually start trusting the whole entire book blindly. Including the stuff that does not have scientific backing. Hey if this book is right about the circumference of the planet, it should be right about these other things too, like homosexuality, alcohol, drinking cow urine, abortion, taboo around menstruation, all of the shit that is written about in these religious scriptures is treated on the same scientific and factual level as the circumference of earth.

This is exactly how religious fanaticism is born.