VATICAN CITY (CNS) -- In the Sistine Chapel, where popes are elected, Pope Francis baptized 16 infants, who, he said, "give us the witness of how to receive the faith: with innocence and with an open heart."

Celebrating the feast of the Baptism of the Lord Jan. 7, the pope baptized seven girls and nine boys, including one set of twins, during a morning Mass with fewer than 300 people in the chapel. Afterward, he led the recitation of the Angelus prayer with about 12,000 people gathered in St. Peter's Square.

While Pope Francis led the baptismal prayers and poured the water over the heads of the infants -- many of whom were squirming and a few of whom cried loudly -- he was assisted in anointing the babies by Cardinals Konrad Krajewski, the papal almoner, and Fernando Vergez Alzaga, president of the commission governing Vatican City State.

Thanking the parents for bringing their children to be baptized, Pope Francis assured them -- as he usually does during baptisms -- that they should not worry about the babies crying or fussing during the Mass, that they should feel free to feed the babies if they are hungry or take off some of their baptismal finery if they get overheated.

After the parents received candles lighted from the Paschal candle, Pope Francis encouraged them not to keep the candle stored away but to have it handy to look at "in difficult moments. This candle reminds us of our Christian roots; never extinguish it in our hearts."

At the end of the liturgy, he asked them to make sure their children know and celebrate the date of their baptism because "it is like a birthday. In baptism they became Christian. Teach your children to celebrate this every year."

In his Angelus address later, he told the crowd gathered in St. Peter's Square that they, too, should know and celebrate the anniversary of their baptism, because "with your baptism, you were born into the life of grace."

In baptism, he said, "it is God who comes into us, purifies, heals our heart, makes us forever his children, his people, his family, heirs to paradise."

"God becomes intimate to us and he does not leave us anymore," the pope said.

Christians should pause, he said, and ask themselves, "Am I aware of the immense gift I carry within me through baptism? Do I acknowledge in my life the light of the presence of God, who sees me as his beloved son or his beloved daughter?"

Pope Francis asked everyone in the square to make the sign of the cross in remembrance of having been baptized in the name of the Father, the Son and the Holy Spirit.

In addition to thanking God for the gift of baptism, the pope told people in the crowd that they also should give thanks "for the parents who brought us to the font, for those who administered the sacrament, for our godfather and godmother, for the community in which we received him."

He asked the crowd to pray for the 16 babies he baptized that morning, "extending these prayers to all the children who will receive holy baptism in these days."