How can it indeed. For most people it seems to be a religious belief that gay marriage is a problem. In the modern world however (or in my country at least) people realise that trying to convince others of their religious beliefs tends to backfire spectacularly so those who oppose gay marriage instead try to find a secular justification for their disapproval and it never seems to work. Either they claim that gay parents damage children, something that becomes legal before gay marriage in many countries and is therefore nothing to do with marriage. Or they go down the slippery slope route, trying to claim that allowing gay marriage will allow other breaks from tradition that scare us all. It makes you wonder whether the anti gay crowd reacted to Saudi Arabia's legalisation of female drivers by claiming that even though women can drive the reform needs to be voted against just in case it paves the way for radical purple haired feminists that want to keep men in a dungeon to be milked like cattle

He sacrificed himself to himself as a loophole to his own rules. It's entirely in God's control whether or not someone goes to hell, if he wants to forgive us for the sins that we seem to find nearly impossible not to do he could either get us to actually do something good to make up for them or he could just blanket forgive us. Either way the blood sacrifice is an unnecessary step

I don't find it useful to point out who happens to be smarter because I doubt anyone would be willing to change their mind while they're being called dumb but the main ways intelligence is measured is by IQ tests and level of education achieved. Both of these things are negatively correlated with religiosity so as a statistical fact atheists seem to be smarter but there may be other aspects of intelligence that are harder to measure that Christians would score better at. Who knows

All I really want to ask is how you know any of this but since that doesn't get to the minimum word requirement I'll ask you to describe your experience of building up this belief