Even great saints had at times succumbed to sin, Pope Francis said Tuesday during his Mass at the chapel of the Santa Marta residence.

“During the Christian journey, the journey the Lord has invited us to undertake, there is no saint without a past and no sinner without a future,” the Pope said in his Jan. 19 homily, according to Vatican Radio's translation.

The Roman Pontiff based his reflections on the day's first reading, and spoke about King David as a saint who nonetheless committed some serious sins.

“The life of this man moves me,” the Roman Pontiff said, speaking of David.

"A saint and a sinner. A man who managed to unite the kingdom, he was able to lead the people of Israel. But he fell into temptation,” the Pope said. He recalled how David committed murder in order to hide having committed the sin of adultery.

“When God sent the prophet Nathan to point this reality out to him, because he was not aware of the barbarity he had ordered, he acknowledged his sin and asked for forgiveness.”

Pope Francis uses David's life as an example of how even saints sinned and were tempted. God chose the young David to be king, even though he did not fit the role by human standards.

God rejected Saul "because his heart was closed", and chose David because “the Lord looks into the heart.”

"We are often the slaves of appearances and allow ourselves to pursue appearances: ‘But God knows the truth’,” the Pope said.

The Roman Pontiff recounted the story of the prophet Samuel choosing David as king, even though he was the youngest of Jesse's seven sons.

God told Samuel to anoint him, and “the Spirit of the Lord rushed upon David,” the Pope said.

“The whole of David's life was the life of a man anointed by the Lord, chosen by the Lord.”

Pope Francis looked at the question of whether God made David a saint.

“King David is saint King David, this is true, but he became a saint after living a long life,” the Pope said.

Although David would later commit adultery and murder, “his life went on,” Francis explained. “He suffered personally following the betrayal of his son, but he never he never used God for his own purpose.”

The Pope recounted how, in the face of insult, David would say: “It’s what I deserve.” He added that David was magnanimous, and did not killed Saul.

“We have all been chosen by the Lord to be baptized, to be part of his people, to be saints,” the Pope said.  

“We have been consecrated by the Lord on the path towards sainthood. Reading about this life, the life of a child — no… not a child, he was a boy — from boyhood to old age, during which he did many good things and others that were not so good.”