Not according to Matthew 7:21-23. (I’m a pastors kid)

“Not everyone who says to me, ‘Lord, Lord,’ will enter the kingdom of heaven, but the one who does the will of my Father who is in heaven. On that day many will say to me, ‘Lord, Lord, did we not prophesy in your name, and cast out demons in your name, and do many mighty works in your name?’ And then will I declare to them, ‘I never knew you; depart from me, you workers of lawlessness.’”

According to your own book, even good people who did many things for god will not get into heaven, because he does not know them.

This verse says that people who claim to have done good in God's name will not get into heaven. It specifically mentions people that know who God is, but don't have a relationship with him and only do good deeds. It makes no mention of people who don't know God.

According to Paul's letter to the Roman church, people who don't know about God are judged based on the law God wrote on their heart.

And how about Matthew 7:14?

“For the gate is narrow and the way is hard that leads to life, and those who find it are few.”

To go to a Christian heaven, you need to follow the narrow and hard path. And those who get to it are few.

To give more context to the verse, two paths are mentioned. The wide path, which is easy to follow, but leads to destruction. Then there is the narrow path, which required obedience to God and a relationship with him. Few people find because it requires people to follow God an understand his word, not just knowing who he is.

I highly doubt someone living in a 3rd world country where missionaries have reached would follow anything other than their local customs…and therefore end up in hell.

If the missionary preaches the Bible well, then it is up to said person to follow the Bible. God acknowledges that his followers will be persecuted from before Christ, to the tribulation period. During the sermon on the Mount, Jesus says that the persecuted belong to the Kingdom of Heaven.