Will Jews, Buddhists, and all others who truly believe in God but not that Jesus is God, and who adhered to the Ten Commandments and who have done charitable acts throughout their lives, be excluded from getting into Heaven solely because of their non-belief in the divinity in Jesus?
Per Scripture, the only way to heaven is by putting our trust in Christ and accepting His free gift of salvation.
The question you pose is based on a common misunderstanding of the relationship between how "good" we are and whether or not we are "good enough" to get to Heaven. The problem is that not one of us has ever kept the Ten Commandments, much less the hundreds of other laws in the Bible, and therefore not one of us is "good enough" to get to Heaven on our own merits.
There's a much more complete explanation of this here.
A longer version of the same answer would go like this:
First, everyone on earth has sinned, save Jesus.
When you examine it, every one of us has broken each and every one of the Ten Commandments, if not in deed, then in heart and in intent. For example, perhaps we've never committed adultery physically, but as Jesus said, if we've looked at someone with lust, we've committed adultery in our hearts.
We've all broken the other Commandments in spirit as well, but even if one of us has squeaked away with not committing all of them, it doesn't matter. The Bible tells us that if we've broken even one, we're guilty.
So, the none of these people are sinless by the standards laid forth in Scripture.
Romans 1 touches on the subject of whether or not we are held guilty if we've never heard the Gospel message. It lays out a few truths:
Their unbelief and rebellion against God meant that their children, their children's children, and so on were not taught about God. It's not His fault, it's theirs. Because they chose to rebel when they knew the truth, and didn't teach their children, they doomed their children to not knowing the truth of God. This is one reason that Proverbs 22:6 is important. (Again, KJV)
In Romans 2 (KJV), we read:
These theoretical people you mentioned are guilty. Scripture here tells us that "he shall perish without law". They will perish because they have sinned, and ignored the conscience that God has placed in each and every one of us.
Finally, it should be noted that even in civil, earthly law, ignorance of the law is not an excuse for breaking the law.
If I were to carry a concealed weapon in a state that doesn't allow concealed carry, for example, and I was arrested, would I be able to avoid the consequences by telling the Judge "I didn't know"? No. I'd be punished according to the law, whether I intentionally broke the law or not.
As we saw in Romans 2 (quoted above), the Bible tells us that God will not accept ignorance as an excuse. They will perish without the Law, as God's word states, because they have sinned and broken the law, not because they have rejected Jesus. Accepting or rejecting Jesus is the only way to be saved. He pays the penalty for our guilt. However, the reason we are guilty is not because we didn't accept Him, it's because we chose to sin.
We can try to blame God all we want, and we can even try to blame the ancestors, but the simple fact remains that these people will be condemned because of their own sin.
Fundamentally, Christianity doesn't believe that anything you do gets you into heaven. You can do good things, and not be saved. You can do bad things, but be forgiven. Who you are, and what you do is, sad to say, irrelevant. From God's perspective, "even our righteousness is as filthy rags." To believe that our poor power to add or detract is a fundamental misunderstanding of how truly incredibly large God is. Its like thinking that we can use a lighter to break a country out of a cold snap. We're too small, and he is too big.
Christianity, in its most basic form, simply says that God saves people.
(Yes, we can get into questions about whether there is first-order volition and predestination and all that - but this isn't the point. You might also ask why God doesn't save everybody - and that would be a good question - but does it make sense to blame a fireman who saved half of the people in the burning house for the deaths of the other half who refused to leave?)
It doesn't matter how good you are, only if God has loved you.
A rejection of the divinity of Jesus is a rejection of the belief that you cannot save yourself. Either we accept that we are not able to save ourselves (and hence ask Jesus to save us) or we try to be own our own Redeemer, in which case, we get precisely the Lord we requested.
Let me attempt to briefly address another issue here. Implicit in this question is an assumption that going to heaven is good and desirable, while going to hell is bad and undesirable.
Why is it desirable to go to heaven? What is in heaven that a Muslim or a Buddhist would want?
I think that our cultural sensibility has so effectively clouded the true meaning of heaven, that we only have left this vague understanding that heaven is somehow good, while hell is somehow bad, but we're not really sure why. Perhaps it's because heaven seems less fiery than hell, and because people speak well of heaven, but poorly of hell. But surely we don't decide our eternal fate on the temperature on the thermostat.
Let me suggest that heaven is heaven simply because it's where God is. Heaven is heaven because we get to commune with God, and no other reason. If God were in Hell, then his very presence there would make hell heaven. And vice versa. If God were absent from heaven, then heaven would cease to be heaven, and would thus become hell.
The God of the Bible is full of love and grace, giving life to the unworthy and giving them all a chance to turn to him through the death of his son. He loves us enough to tell us that our works are like filthy rags (Isaiah 64:6... literally "menstrual cloths"), and that we can never do anything to earn God's love, because we've all sinned and failed.
Of course, if you view heaven as being with God, and your desire is to be with Him, then at this point you're going to be frightened. With the disciples, you're going to ask yourself "Who then can be saved?" (Mark 10:26). If God is so demanding and we've all failed so horribly that there's no way we can be with him, then we're in a very bad position. God is all that is good, and we're in a state where we're going to be completely rejected by him, and without him for all eternity.
This is where Jesus comes in. Jesus paid the penalty. His death was fully sufficient to pay the penalty we owe God. It's not simply that God forgave the sin, but that the sin was properly paid for. God grants eternal life with him to those who depend on Christ's sacrifice, and not their own good works, for salvation. And he loved us enough to send Christ, knowing that there's no way that we'd be able to generate enough good works on our own.
So the question is: do you want to be with such a God? Do you want to worship a God who is both demanding but loving and forgiving? If the answer is yes, then there's only one way: through Jesus (John 14:6). If the answer is no, then any other belief can accomplish the task of keeping you from Him, but of course, not every belief accomplishes exactly what it promises. (Matthew 7:14)
So in a nutshell: Those who don't have faith in Christ as the sacrifice for their sin will not go to heaven. But the bigger answer is that they don't really want to.
You can find answer to this question in scriptures where people were asking the same question. Acts 16:30-31
Well, God wants to save everyone - that's what He wants. But it is not His sovereign will, or else everyone would be saved, which we know isn't true. Also, it would depend on if Jesus had died on the cross yet. Before Jesus died on the cross, the Jews would make sacrifices to please God's wrath. It wasn't the act of the sacrifice, but it was the faith they had placed on God that he would save them. Basically they were looking forward to the cross. Now though, Jesus has died on the cross and it is said in the Bible that we must believe that yes, Jesus is God, and that He was a man, not an angel or "holy man." He was 100% God and 100% man.
Also, just because you are good, you are not good enough in God's eyes which is why God sent His son Jesus so we can be called righteous through Jesus, not through our good deeds. God says that those who are saved will do good works because we are saved not to "keep our salvation" or anything like that.
So, I don't think Jews, or Buddhists, or people who believe in a god will go to Heaven because it is clearly stated that everyone knows that there is a God or creator. Aka general revelation.
Oh and this is from a 12 year old's knowledge so I am definitely no Bible Scholar xD
Jesus said something like : Don't go looking for the Kingdom of Heaven some place else. The Kingdom of Heaven is within/among you (and outside you - according to Thomas.)
The KOH is where you are while you are getting to know God. When a person centers his life on God he/she is in the KOH. Any believer in God can do this. Since the idea of Heaven is monotheistic, a non-believer will not be able to enter it. This is not the same as a life after death, which is a belief of many religions.
For Christians you can think of Jesus's life, or even Jesus himself, as the KOH into which we enter and as Paul said "have Christ within us, " and "to be in Christ." It is a teaching of all Christian Churches that Christ is the life that sustains humans, and so as long as we are alive, we cannot be separated from Christ (as Paul said,) only we may not know of Christ if we are ignorant of the Biblical teaching. The gradual awakening of this knowledge of Christ within us is the result of stepping into the KOH. Any person can take this step, whether an isolated native in the wilderness, or not.
If you are wondering what will happen after death, I have no idea.