On what basis do you make that assertion?
As a rational being, why would I want to voluntarily end my existence? As a rational being, why would I want to end someone Else’s existence unless they were a direct threat to my continued existence?
Lots of people want to end their existence. Some out of a feeling of remorse, which you may not find rational. Some because the concept of existing is no longer entertaining to them.
Why would I trust anyone Else’s words that might contravene what my own intelligence it telling me about how my life should be lived?
You were the one who pointed out the limits of your intelligence. I know there are limits to mine. Deciding what is real based solely on my own intelligence seems like a bad idea.
Especially when there are competing religions offering those words...
I don't have any problem applying my intelligence to what competing religions, or even competing gods say.
What is a "God"? If you accept the definition of an Omnipotent/Omniscient being that exists beyond our own mortal selves... then such a being would be as much, if not more, advanced than we are to any other lower lifeform we know of.
Lots of people want to end their existence.
Lots of people do things that aren't rational. As long as they aren't hurting anyone else directly, why should we get in their way? It isn't our life. It's theirs.
Deciding what is real based solely on my own intelligence seems like a bad idea.
Why? You'd trust someone else to come up with those ideas for you? Are you sure they have your best interests at heart? If you are that sure, then why so uncertain about your own abilities in discerning the answers to such questions yourself? Seems like you are trying to put off having to come up with hard answers for yourself...
I don't have any problem applying my intelligence to what competing religions, or even competing gods say.
Which is more than enough intellectual horsepower to work through the calculus to come up with those answers for yourself despite your protestations otherwise. ;-)