“David was a saint. He was a sinner. A sinner, and he became a saint. Solomon was rejected because he was corrupt,” the Pope said Feb. 8, adding that “someone who is corrupt cannot become a saint.”

Speaking from the small chapel inside the Vatican's Saint Martha guesthouse where he lives, the Pope centered his reflection on the day's first reading from the First Book of Kings, which recounted how God became angry with Solomon for worshiping false gods that his wives believed in.

In the reading, God told Solomon that he would “deprive you of the kingdom.” However, for the sake of David's righteousness, God said he would take it from Solomon's son instead, leaving him only a small portion of his kingdom.

The reading recounted something “a bit strange,” Francis said, because God took away the kingdom from Solomon, but didn't say whether he had committed any major sins. However, from scripture we know that David had difficulties and was a sinner.

Despite this fact, David is a saint, while Solomon – who at the beginning of his reign had been praised by God for seeking wisdom rather than riches – was condemned because his heart had “turned away from the Lord.”

This can be explained, Francis said, by the fact that David, knowing he had sinned, asked for forgiveness, whereas Solomon was praised throughout the world, but never recognized his fault when he distanced himself from the Lord and followed false gods.

“The heart of Solomon was not entirely with the Lord, his God, as the heart of David, his father, had been.”

Francis said the problem comes from a “weakness of heart,” which, he said isn't like a typical sin that is recognized “immediately” after being committed. Rather, this sort of weakness, he said, is more subtle, and is “a slow journey that slides along step by step, step by step, step by step.”

“Solomon, adorned in his glory, in his fame, began to take this road,” he said, explaining that “the clarity of a sin is better than weakness of the heart.”

Despite being praised for his wisdom, “the great king Solomon wound up corrupted: serenely corrupt, because his heart was weakened,” the Pope said, adding that the same danger exists for every Christian.

A man or woman with a weak heart is “defeated,” he said, and “this is the process of many Christians, of many of us.”

While many people might be able to say “No, I haven’t committed grave sins,” Francis countered, asking “how is your heart? Is it strong? Does it stay faithful to the Lord, or is it slowly sliding away?”

This subtle sliding away can happen to anyone, he said, saying the remedy to ensure this doesn't happen is to always be “watchful” and vigilant.

“Guard your heart. Be watchful. Every day, be careful about what is happening in your heart,” he said, explaining that a person becomes corrupt “by following the path of weakness of the heart.”

Pope Francis closed his reflection telling the congregation to “guard your heart at all times” and to ask themselves how their relationship with the Lord is going, urging them to “enjoy the beauty and the joy of fidelity.”