What does Luke 17:19 mean?

Jesus has healed ten lepers. Only one, a Samaritan, returns to thank Him and praise God. He recognizes what the Pharisees do not: Jesus performs miracles under the power of God; Jesus is of God (Luke 17:11–18).

The term "progressive revelation" refers to the fact that God reveals truths about Himself gradually, over the course of history. Throughout the ages, people have been saved by God's grace through believing what God reveals to them (Hebrews 11). This Samaritan understands and accepts who Jesus is to the extent of what he understands at this point.

Because of that, Jesus says his faith has made him "well." The Greek for "made well" can mean preserved, saved from death, brought out safely, or freed from disease. It can also mean "saved" spiritually. Bible scholars debate over what Jesus means, here. Unlike the paralytic, He does not overtly state, "Man, your sins are forgiven you" (Luke 5:20).

The Samaritan is healed physically. It's possible that Jesus is summarizing what has happened and commending his faith unto physical restoration, just like the other nine who left to show themselves to the priests before they showed signs of healing. The more natural interpretation, however, is that this Samaritan, unlike the nine presumably Jewish lepers who did not return, has received forgiveness of his sins.

This Samaritan's understanding of the situation is in stark contrast to the Pharisees. He knows Jesus heals by the power of God. The Pharisees claim Satan empowers Jesus (Luke 11:14–15). The healed man understands that Jesus reveals the presence of God: the coming of God's kingdom. The Pharisees still ask when the kingdom is coming (Luke 17:20–21).