Vatican City, May 31, 2013 / 08:00 am

Christians often act like they are "going to a funeral procession rather than to praise God," Pope Francis declared, urging believers to spend time praising God so they are not slaves to their sorrows.

"You here at Mass," the Pope said in the chapel of St. Martha's House, "do you give praise to God or do you only petition God and thank God?

"Do you praise God?" he repeated, pointing out that this "is something new, new in our new spiritual life."

Anticipating a common excuse for not praising God, he said, "'this Mass is so long!'"

"If you do not praise God, you will never know the gratuity of spending time praising God, the Mass is long. But if you go with this attitude of joy, of praise to God, that is beautiful! This is what eternity will be: giving praise to God! And that will not be boring; it will be beautiful! This joy makes us free," Pope Francis said in his May 31 homily.

He based his words on the daily readings, one from the prophet Zephaniah and the other from Luke's Gospel, which recounted Mary visiting her cousin Elizabeth.

The Old Testament reading contains the exclamation "Rejoice! Cries of joy, the Lord is in your midst," while the story of Mary's visit recalls how John the Baptist "rejoices" in Elizabeth's womb when he hears Mary's greeting.

Both of the readings speak of joy, "the joy that is celebration," the Pope said.

But "we Christians are not so accustomed to speak of joy, of happiness. … I think often we prefer to complain," he stated.

"Without joy," he added, "we Christians cannot become free, we become slaves to our sorrows. The great Paul VI said that you cannot advance the Gospel with sad, hopeless, discouraged Christians. You cannot."

Being joyful "comes from praise, Mary's praise, this praise that Zephaniah speaks of, Simeon and Anna's praise: this praise of God!" the Pope preached.

Through the guidance of the Holy Spirit, who is "the author of joy, the Creator of joy," Pope Francis said that Christians learn to praise and become joyful, which leads to "true Christian freedom."

He finished his homily by pointing to Mary as the model of "this praise" and "this joy."

"The Church," the Pope noted, "calls her the 'cause of our joy,' Cause Nostrae Letitiae. Why? Because she brings the greatest joy that is Jesus."

"We need to pray to Our Lady, so that by bringing Jesus she gives us the grace of joy, the joy of freedom. That it gives us the grace to praise, to praise with a prayer of gratuitous praise, because he is worthy of praise, always."