An estimated 10 million Roman Catholics are expected to pass through the Holy Door, a symbol of the threshold to salvation, during a yearlong celebration dedicated to the theme of mercy.

But, Pope Francis warned Wednesday, be wary of fraudsters asking for a soul toll.

“Be careful,” he exhorted, according to the Catholic News Service. “Beware of someone who is sly or sneaky who tells you that you need to pay. Salvation cannot be paid for; salvation cannot be bought. Jesus is the door, and Jesus is free of charge.”

Francis called for the Jubilee, or Holy Year, to highlight the need for mercy, he said in an interview this month with an Italian magazine, Credere. Typically, they are celebrated every 25 or 50 years and are focused in Rome, but this year bishops will open Holy Doors in local places of worship around the world.

“To pass through the Holy Door means to rediscover the infinite mercy of the Father who welcomes everyone and goes out personally to encounter each of them,” the pope said before the opening ceremony last week. “This will be a year in which we grow ever more convinced of God’s mercy.”

On Monday, police in Rome said they had seized 3,500 fake Vatican parchments that were being sold as keepsakes of the Holy Year pilgrimage, The Associated Press reported. The genuine parchments are personalized and sold by the Vatican for $8 to $40 to fund the pope’s charitable efforts, but $76,000 worth of knockoffs were found at a souvenir shop near St. Peter’s Basilica.