I'm not keen that heaven is for believers and non-believers don't make it.
I was raised Catholic, and I sort of still am, but don’t believe that at all. I don’t know anyone who does either. I can’t say exactly what Catholic teaching is (I’m never did catechism at school or anything) but I think it is about intent. I think to get to heaven people need to demonstrate love for others. And need to be sorry when we don’t love others. And that’s pretty much it. Those who do that get eternal life with god - our sins washed away and only our goodness remains so there’s no badness in heaven. I believe that organised religion (of all types) helps some of us be more loving, but others don’t need that guidance (and plenty misuse it). Faith is an option for those of us who need an obvious, direct relationship with god to keep us on the straight and narrow.
This sort of links with Jesus saying we need to go through him to get to the Father - the new commandment to love one another is what he brought to us. The old commandments were helpful in telling us how to actually behave but humans had made it all complicated and made up a whole lot of other rules - we missed the important point. I also think that’s what I see in some of the Church’s more recent teachings (eg burning witches, homosexuality being wrong etc). To me, to be Christian is to follow Christ in his message of love.
I do believe in hell though. If a person acts with no care of others, or is not sorry when they cause pain then they don’t get to heaven. The don’t get to live in a place of pure grace (goodness, happiness, love). I think they get actual nothingness, emptiness, true death.
I don't understand the logic of sacrificing Jesus for our sins.
I think there are two bits to this. For both, I think it is important to see Jesus as a teacher and guide as well as god. God would not have come to earth is humans were already on the correct path - he came in the form of Jesus to help us get there.
Firstly, humanity was (and still is tbh) obsessed with vengeance. The idea that when someone does wrong we must make them pay (and lots revel in watching the sinner suffer). That is the exact opposite of love. In one way, I think Jesus died to tell us all that the payment for sins has already been made and we need to stop torturing each other.
Secondly, there’s the problem of forgiveness. Jesus taught us that we are forgiven if we are sorry for our actions. That’s great - a clean slate just by being sorry! But it is really hard to accept that the worst among us get forgiven too (if genuinely sorry). But Jesus (tortured to death having done nothing wrong) demonstrates that if we love enough we can forgive even those who harm us terribly (as he forgave those who put him to death).