If you ever visit Chichen Itza, you can see murals depicting their ceremonies. One of them shows how two teams would compete in some kind of sport involving hoops and balls, and the leader of the winning team would be sacrificed.
And everyone involved thought this was awesome, because it was a great honour something something the gods something sacrifice for your people something.
With our modern sensibilities and rationality, it's absolutely mindboggling.
It's really not mindboggling at all, in regards to modern sensibilities. It's still regularly going on today.
It's identical to blowing yourself up to kill infidels (argued as a great honor by those advocating it, you're the chosen one). And it's similar to crashing your plane into a ship as part of the Shinpū Tokubetsu Kōgeki Tai, commiting suicide, sacrificing your life to defend the empire and emperor. To be clear, I'm not adding any commentary on the practices, merely noting the historically recent nature of very similar concepts.
One of the most universal tenets of popular religions, and typically most spiritual belief in general, is self-sacrifice.
With these forms of suicide, it's an other-world calling that is meant to be greater than the value of your own life. Modern sensibilities perhaps make it more shocking, however I don't see anything changing about this core concept and its practice in the next century. So long as most religions function on degrees of self-sacrifice, somewhere someone will be taking that to the next step and demanding people sacrifice their lives to some proclaimed higher calling.
I think that such self sacrifice among the Aztecs is very different to the politically and militarily oriented sacrifices you mention.
The former has no reasonable or practical reasoning.
The later - does, as I think any service member will understand. Every mission has some degree of likelihood that one will face death, some are just willing to up the ante to . a much greater level. The belief in some kind of 'special heaven' is not really the motivating force, it just kind of makes it easier to do.
And everyone involved thought this was awesome, because it was a great honour something something the gods something sacrifice for your people something.
With our modern sensibilities and rationality, it's absolutely mindboggling.