Well that's just it, science criticises itself to huge levels until only the most viable explanation is remaining. That's how science works, poor hypothesis are weeded out quite quickly.
Sure, but the quote you provided that "they can't all be right so it's best to assume they are all wrong" is logically absurd. If two or more are mutually exclusive it's clear they can't all be right but it just doesn't follow that none of them are. It's not necessarily a bad thing to give them all an equal status until they have been investigated but to say "they're not all right so assume they are all wrong, case closed" is absurd.
Religions, forbid critical thinking about their tenets and encourages blind acceptance without questioning.
Really?
Is that why Paul lauded the Bereans for studying the Scriptures to test his teachings? Is it why he told the Thessalonians to "test all things, hold fast what is good"? Is it why John wrote to test the spirits?
A religion that doesn't allow critical thinking is a religion not worth following. Anything that tries to ignore testing usually has something to hide.
You can see that on this and any other religious forum. You're quite happy to ignore established scientific theories but you would never dream of turning that same level of questioning to your bible.
Speaking in generalities doesn't really help. If Scripture contradicts Scripture, or Scripture contradicts life, then either Scripture is wrong or we misunderstood it (or, potentially, we misunderstood life). Maybe the established scientific theory is wrong. Nowadays there seems to be an increasing tendency to look for strength in numbers, as if lots of people in agreement changes what is true. After all, when Galileo proposed the absurd notion that the earth revolved around the Sun he was decried as a heretic - everybody knew the sun revolved around the earth.
Hitchens quote stands as none of the religions encourage this, they all insist that theirs is the one true religion and the rest are false. In this sense they are partly right.
It doesn't stand because it starts with a fair observation and ends with an absurd conclusion. If there is no god then all religions that believe in a god are wrong. If there is a god then the chances are that at least one of the religions that requires the existence of a god is correct. If there is a god then Hitchens is demonstrably wrong; if there is not then Hitchens is still using fatally flawed reasoning. The flaws are further highlighted because his proposed solution is itself essentially a statement of faith. Either there is a god or there isn't. Those who have an active belief in the existence of god can be called theists; those who have an active belief in the non-existence of god might be called antitheists (to borrow the term from MarkFL). Neither can prove their case so, according to Hitchens we must regard them both as being wrong. But to say they are both wrong is absurd, because either there is a god or there is not. Either theists are right, or antitheists are right. It's not logically possible for both to be right, or for both to be wrong.
It's a perfectly fair conclusion to say that, faced with many competing claims and counterclaims, we can't be sure which is correct without looking into them in more detail. But to conclude that everybody must be wrong is clearly absurd.