For example if there was a Jew/ Muslim/ Shinto/ Atheist who devoted their lives to doing good works, charity, looking after people and never did a bad deed, would they be excluded from Heaven?
I think there's two layers to this:
1. The thread's title question, "Do Christians believe every non-Christian will not go to heaven" and
2. Would a non-Christian who dedicated themselves to good works/being good be excluded from heaven.
To answer the first,
some Christians believe that all non-Christians will be excluded from the future world, but by no means all. Christian thinking has been varied and diverse throughout the history of our faith, and we could say that there is something of a spectrum of ideas. Think of it like this, one one end you have Christians who believe that all non-Christians are bound to hell, forever and ever and ever and ever; on the other end you have Christians who believe that, eventually, everyone will share in the life of God and, ultimately, hell will be empty. The majority of Christians sit at neither of these two ends, but exist somewhere in the middle between them. It's also worth remembering also that (arguably) the majority of Christians wouldn't even say that all Christians will "go to heaven", and that there will be Christians who will find themselves among the goats and tares (the judgment scene depicted in the 25th chapter of St. Matthew's Gospel isn't between Christians and non-Christians, both those on Christ's right and left are Christians).
Since Christian views on this topic can be varied, there is no singular view that can be offered as an answer. What can be said is that, no, most Christians don't believe that all non-Christians are going to hell/excluded from the life to come.
To answer the second question it's important to understand that every major expression of the Christian faith--Catholic, Orthodox, and Protestant--understands that salvation and our hope and promise of life in the future age isn't based on our being "good enough", it is fundamentally about God's kindness and grace extended to us through Christ, in His death and resurrection. In the strictest sense "heaven" is not a reward for being good and "hell" is not a punishment for being bad. The Christian hope is that God, in Christ, is restoring the world and our salvation is our participation in that work in as much as we, hoping and trusting in Christ, having been baptized, have been united to Jesus and therefore hope in Him to be present in that future world and part of it, in Christ, when all things have been made new. "Hell" is
not that.
Therefore the question is not "What about the Hindu who dedicates himself to trying to live good?" And then speak of "Heaven" as the reward for doing good works in this life, because "Heaven" isn't a reward for doing good or being a good person; it's what the universe looks like after Christ returns and God has made all things new--and our place there isn't dependent on how well we conducted ourselves, or how obedient we were to God's commandments (etc) but rather our place there is rooted in Christ. Therefore the Hindu who finds themselves in the future world isn't there on account of their good deeds, but it would be based solely on the kindness of God in Jesus--the same as what we Christians hope for here and now. The grace of God is such that no one is excluded from what He will do, nobody, flat out nobody is excluded.
Touching on these together then: Quite a good many Christians (a majority even?) would indeed argue, in different ways, that the way anyone can get to Hell is by their own conscious choice--nobody will be in Hell who doesn't consciously
want to be there. Some might argue that this choice is only able to be exercised in this life, others would not. Many Christians simply don't believe in being dogmatic about things which Scripture hardly touches upon and which the Church historically simply has never been dogmatic about and to insist that the only appropriate thing to say is that God is, indeed, good, kind, merciful, and just--and so the ultimate outcome of everything will be, fundamentally, in accordance with His love, kindness, compassion, and justice which He has universally for all, without exception.
To quote St. Isaac the Syrian:
"
In love did God bring the world into existence; in love is God going to bring it to that wondrous transformed state, and in love will the world be swallowed up in the great mystery of the One who has performed all these things; in love will the whole course of the governance of creation be finally comprised."
-CryptoLutheran
