Martin: Peter
Can you show me where the Bible says that an unbeliever is capable of doing good?

Peter: Stop being ridiculous. Is having more faith than anyone in Israel for example not doing good? Jesus regularly went out of his way to praise the works of those the religious conservatives labelled unbelievers on the basis of the bible. What do you think the parable of the Good Samaritan was about? The clue is in the title!

Martin: Peter
Faith is the gift of God, and where does Jesus say they are unbelievers?
And Jesus said to him, Why do you call me good? No one is good except God alone. (Luke 18:19 [ESV])
You will, of course, note that nowhere does Jesus call the Samaritan good.

Peter: "Nowhere does he call the Samaritan good".
That's what your theology leads to. The polar opposite of the point of the parable.
You couldn't make it up.

Martin: No, it's not the polar opposite of the point of the parable. Jesus never calls the Samaritan good, he says he was a neighbour. Be honest and admit it.