It is a strange thing, then, that our Lord praises the man’s faith. What credit did he deserve for that? His faith was not his own. It was not of his own making. It was a gift. Its strength sat not in the will or discipline of effort of the centurion, but rather according to the Lord’s grace and mercy.
But that is the whole point. The centurion does get the credit. It is his faith because the Lord in His mercy, has given it to him. This is the key doctrine of Christianity: The Father gives credit to us for works performed by the Son and blames the Son for our sin. So the Lord gives the centurion faith and then praises him for it. He commands that the centurion pray, then He answers.
Thy Kingdom Come: Lent and Easter Sermons
David H. Peterson