What happens with non-believers who are good?
Verily! You (O Muhammad SAW) guide not whom you like, but Allah guides whom He wills.
And He knows best those who are the guided. (Quran 28: 56)
In this verse it is mentioned that not even the Messenger of Allah guided people but only Allah did and will. We can just give advise people or inform them about islam but the real one who is able to show the truth, who is able to make the sight clear and the heart of a non believer pure, is only Allah! But it is also that, one has to make effort and learn about islam from the heart and pray to Allah to guide him, so that Allah sees that and guides him.
For example, you see sometimes atheists who disbelieved and hated god suddenly became muslims or even christian priests like Samuel Earle Shropshire who convert. You might think its strange right? How did an atheist or a christian priest becomes a muslim. It all starts with a simple step: they question God and their own existence and look in the details of all religions to find out the truth.
Here I would recommend you to check the channel "Muslim Convert Stories" on youtube. There people from different religions talk about what made them to convert to islam.
For example:
Allah says "Take one step towards me, I will take ten steps towards you. Walk towards me, I will run towards you."
It is up to Allah if He wants to guide a disbeliever or not. The disbelievers are also His creation and Allah is merciful, so He guides whom He wills! He also created them so if He wanted to He could have guided everyone.
In Islam, Allah does not misguide people, but certain individuals by their own volition chooses the path that could lead them away from Allah's guidance!
We sent to you [Muhammad] the Scripture with the truth, confirming the Scriptures that came before it, and with final authority over them: so judge between them according to what God has sent down. Do not follow their whims, which deviate from the truth that has come to you. We have assigned a law and a path to each of you. If God had so willed, He would have made you one community, but He wanted to test you through that which He has given you, so race to do good: you will all return to God and He will make clear to you the matters you differed about. (Quran 5:48)
And Allah knows best whats in the hearts, while we know not!
Whoever is guided is only guided for [the benefit of] his soul. And whoever errs only errs against it. And no bearer of burdens will bear the burden of another. And never would We punish until We sent a messenger. (Quran 17:15)