A lot of people cannot understand why God allows children to suffer, and this is a "mystery" even Pope Francis himself cannot seem to find the answer to.

"Why do children suffer?" Pope Francis asked a group of children with serious illnesses or disabilities while he was at the chapel of the Vatican's Santa Marta residence, the Catholic News Agency reported.

"It is the mystery of the Cross," he said, answering his own question, adding that it's an answer people will find only when they gaze upon the Cross. When they do this, Pope Francis said they could ask God, "Why is Your Son there?"

God's answer will always be, "Even my Son suffered," the Pope said, adding that this is where people can actually find strength.

"Your strength is there: the loving gaze of the Father. The Trinity, the Eucharist, God's grace," he said.

"The suffering of children is a mystery. And one can enter into the mystery only if the Father looks upon us with love," the leader of the world's 1.2 billion Roman Catholics said.

Pope Francis told the sick children that he has nothing but the utmost admiration for their strength and courage. "You are the little heroes of life," he said.

Most of the children were only between the ages of seven and 14, while some of them were just a few years old.

When he recalled that some parents were told by doctors to have abortion because their children might be born sick, he once again lauded them for choosing to let their children live no matter what happens.

"Never, never does killing a person resolve a problem. Never," he stressed.

Pope Francis assured the children and their parents in the chapel that he is with them on their journey towards faith and healing. He also expressed his gratitude to the parents for leading by example.