In his homily during morning Mass Sept. 4, the Pope said that the hearts of men and women are like "a battlefield" where the spirit of God and the spirit of the world "fight each other."

"We all have what we can call these two 'spirits': The spirit of God that leads us to do good deeds, to charity, to brotherhood, to adore God, to know Jesus, to do many works of charity, to pray; and another, which is the spirit of the world that leads us to vanity, pride, arrogance, gossip -- an entirely different path," he said.

In his homily, the Pope focused on the day's reading from St. Paul's First Letter to the Corinthians in which the apostle says that Christians are given the spirit of God "so that we may understand the things freely given us by God."

God's spirit is a "great gift," the Pope said, and the only way to protect it and "drive away the spirit of the world" is by doing a daily examination of conscience.

"It is very simple: we have this great gift, which is the spirit of God, but we are fragile, we are sinners and we also have the temptation of the spirit of the world," he said. "In this spiritual combat, in this war of the spirit, we need to be winners like Jesus."

If Christians do not reflect on "what happens in their hearts," he added, they risk becoming "like animals who understand nothing and go by instinct."

"We are not animals, we are children of God, baptized with the gift of the Holy Spirit," Pope Francis said. "That is why it is important to understand what happened today in my heart. The Lord teaches us to always do, every day, the examination of conscience."