The fact that there’s hell proves that God doesn’t show mercy to everyone.
No it doesn't.
Hell is complete separation from God; people are in hell after they die if they died in their sins, rejected God's grace, mercy and love and continued to live for themselves and try to save themselves.
As I've said, if someone is not reconciled to God when they die, if they do not have forgiveness of sins and new life through Jesus, then they cannot be with God. And because there is life after death, they will continue to exist, for all eternity, in a state of being without God and with no prospect of forgiveness for their sins.
If you don't believe in the concept of human choice, or being able to decide to respond to Jesus' invitations and accept God's free gift of eternal life, then you are left with salvation on God's whim - "I'll choose you, but not you". I don't see that in Scripture, I see a God who says "
Everyone who comes/believes/receives/eats "etc. Not everyone will come, respond to the invitation or accept that Jesus died for them. Some may never hear, some may hear, but think "that's not for me; I'm unworthy/not good enough/have committed
x sin". Some may hear this invitation but don't believe it; they don't believe they need to come to Jesus to be saved, they believe that God loves and will save everyone and their good deeds are good enough. Or they may feel they don't need saving at all, that their bad deeds have not been bad enough. Some might refuse, point blank, to think about God at all, and that might be because they are confusing God with the church, have been badly let down by the church, or cannot accept a god who, they believe, causes suffering.
It's easy to dismiss such people and claim that they were never chosen, (I'm not saying you're doing that), or that they weren't predestined to believe, but I don't believe that it's accurate.
If you adopt the scenario of salvation being random and it's up to God to choose which of us to save, then it must make for a rather uncertain life; "am I chosen or not, could I be deselected if I mess up enough times/miss God's plan for my life?" If God can choose on a whim then presumably he can change his mind, also on a whim.
Jesus told us to go and make disciples and to be his witnesses - he did not say "God only loves a few and you do not know who has been chosen, so just preach to everyone." Thank goodness! Fancy working hard/risking your life to preach the Gospel and then find out it had all been a waste because the person you are talking to hasn't been chosen for salvation.
So if God loves everyone without condition, there’d be no need for hell.
Except that some will not accept God's love, forgiveness and reconciliation through Christ.
Paul said to the Corinthians "we implore you on Christ's behalf; be reconciled to God", 2 Corinthians 5:20 - he was urging them to accept God's salvation, or to make sure they had accepted it.
Otherwise the message of the Gospels might just as well be, "live your life however you wish and believe whatever you like; of God has chosen you for salvation, you'll be saved regardless. If he hasn't chosen you, whatever you do is irrelevant because you're going to hell anyway."
That's not love.