Then He said to Thomas, "Reach your finger here, and look at My hands; and reach your hand here, and put it into My side. Do not be unbelieving, but believing." And Thomas answered and said to Him, "My Lord and my God!" Jesus said to him, "Thomas, because you have seen Me, you have believed. Blessed are those who have not seen and yet have believed."
John 20:27-29

What does God owe us? Exactly! Nothing. But He not only gives us salvation through Jesus Christ, He gives us the faith to believe. This is important since we receive salvation through faith in Jesus, and left to ourselves, no one would ever believe! (John 6:44, 1 Corinthians 2:14)

It is also wonderful that the Lord condescends to grant the gift of faith even to those He came to save, who are having a hard time believing.

The women who were first at the tomb told the disciples about the Resurrection. They didn’t believe (Mark 16:11, Luke 24:11).

So Jesus showed Himself to the disciples. They reluctantly believed. And when they told Thomas (who didn’t go to the meeting that evening) he didn’t believe (John 20:25). So Jesus showed himself to Thomas, resulting in Thomas believing.

Here is the point: Jesus didn’t have to do any of that for any of them. But He did. Why? Because He came to save His people from their sins, and He will save them—even if they resist believing!

I would imagine that if we thought about it, many of us could remember ways in which the grace of God overcame our resistance!