God is always with us, Pope Francis said on Sunday, and he will never leave us to walk through life alone.

Speaking during his homily for Pentecost Sunday in Rome, the Pope reminded his audience of the day the early church first received the Holy Spirit, which "frees us from the condition of being orphans".

In our society today, many people live as though they are orphaned, Francis continued. We see this, he said, "In the interior loneliness which we feel even when we are surrounded by people, a loneliness which can become an existential sadness; in the attempt to be free of God, even if accompanied by a desire for his presence; in the all-too-common spiritual illiteracy which renders us incapable of prayer; in the difficulty in grasping the truth and reality of eternal life as that fullness of communion which begins on earth and reaches full flower after death".

But we are called to a different way of life.

"Being children of God runs contrary to all this and is our primordial vocation. We were made to be God's children, it is in our DNA," he said.

"But this filial relationship was ruined and required the sacrifice of God's only-begotten Son in order to be restored. From the immense gift of love which is Jesus' death on the cross, the Holy Spirit has been poured out upon humanity like a vast torrent of grace. Those who by faith are immersed into this mystery of regeneration are reborn to the fullness of filial life."

The Holy Spirit unites Christians to one another and to Christ, the Pope added.

"Strengthening our relationship of belonging to the Lord Jesus, the Spirit enables us to enter into a new experience of fraternity. By means of our universal Brother – Jesus – we can relate to one another in a new way; no longer as orphans, but rather as children of the same good and merciful Father.

"And this changes everything! We can see each other as brothers and sisters whose differences can only increase our joy and wonder at sharing in this unique fatherhood and brotherhood."

Pentecost, celebrated seven weeks after Easter Sunday – this year on May 15 –  commemorates the descent of the Holy Spirit on to Jesus' disciples after he ascended to heaven. The story is told in Acts 2, and is considered to be of profound importance in the history of Christianity.