Was is the truth about Montzuma and aztec religion?

true. the superiority did have a pretty big impact, but it's not like cortes won every battle or anything and there were plenty where he came pretty close to dying.
there was one night where he was chased out of tenochtitlan and retreated northeast for about a week until he met what he claimed to be 200,000 aztecs, though that's probably not very accurate, considering he had less than a fifth of that number of troops himself, including his tlaxcalan allies and was able to win the battle by leading a cavalry charge. the macuahuitl was better suited for messing people up than it was for killing them, but enough hits could knock him off of his horse and he'd be the next sacrifice.

Not taking anything away from Cortez and Pizarro big cojones, their success in the conquest of incas and aztecs was possible precissely because we are speaking about two monolithically organized and advanced civilizations here. The more primitive and fragmented the indians the most difficult to conquest. Lets look at the Mixton wars at northern Mexico/southern USA or the mapuches at southern Chile and Argentina for instance. The key being there was not a central power to attack and destroy but unlimited groups that could fight independently like a multi-headed hydra and eventually unite and become a big army.

Of course, if these people remained free for centuries after the great civilisations of the Andes and Mesoamerica had fallen to the Europeans, you have to wonder if "primitive" is the right word for them. If the intention is liberty rather than pyramids, you could argue that they were very sophisticated indeed.

like with anything else, a lot of stuff goes into it. i'm not arguing that anybody was more primitive than anybody else, but there were definitely a lot of factors, with different ways of life being only some of them.
there's a lot more space in the great plains of north america than the west coast of south america, after all. and the aztecs were surrounded by people who got sick of being bullied.
but, one thing i will say is that it's difficult to "win the war for good" by taking over somebody's capital when that doesn't exist.