Here’s a ‘religious person’s’ point of view. I am quite keen to leave this broken world and go to be with God, where there will be ‘no more death, or mourning, or crying, or pain’ according to the Bible. I’m looking forward to it a lot. I know other Christians who feel the same way, However, there is also a) an animal instinct to go on living and b) a wish to cooperate with God, so that if he wants me on earth, that’s where I want to be. So I would never kill myself however much I felt like it. Also I have children that I wouldn’t want to be without me yet.
I think these reasons to want to live apply to many other Christians, so if there isn’t earlier mortality among us, they are at least partly why.
I just googled whether Christians are less afraid to die than non-Christians, and found that according to a study in the Journal of Cognitive Science (briefly described and linked to here: https://coldcasechristianity.com/writings/afraid-to-die-youre-probably-not-a-christian/) Christians were found to fear death less than atheists, Hindus or Buddhists. According to this article other studies also support this idea.
So even if we don’t die earlier, our beliefs may make a difference at the end :) On average, of course, not in every case, in spite of the title.