At the celebration in St. Peter's Square, the Pope warns against the “supporters” within the Church and of being of the “right or left before being on the side of Jesus”. At Regina Coeli, prayers for the victims of the London terror attack.

"According to God’s will, a union that is not uniformity, but unity in difference," affirms the Pope who on Pentecost Sunday celebrates Mass sided by cardinals, bishops, and priests in St. Peter's square. During the Eucharistic celebration, after reading the Gospel, Francis pronounces the homily asking for "the grace to make more beautiful the countenance of our Mother the Church". The Pope exhorts us to forgive and correct ourselves: "Only then will we be able to correct others in charity." So let us ask the Holy Spirit "Fire of love burning in the Church and in our hearts, even though we often cover him with the ash of our sins: "Spirit of God, Lord, who dwell in my heart and in the heart of the Church, guiding and shaping her in diversity, come!" In fact, the Pontiff emphasizes, "Like water, we need you to live. Come down upon us anew, teach us unity, renew our hearts and teach us to love as you love us, to forgive as you forgive us".

Today, Jorge Mario Bergoglio remembers, "concludes the Easter season, the fifty days that, from Jesus’ resurrection to Pentecost, are marked in a particular way by the presence of the Holy Spirit. The Spirit is in fact the Easter Gift par excellence. He is the Creator Spirit, who constantly brings about new things". So, Francis points out, " Today’s readings show us two of those new things. In the first reading, the Spirit makes of the disciples a new people; in the Gospel, he creates in the disciples a new heart. On the day of Pentecost, the Spirit came down from heaven, in the form of “divided tongues, as of fire… that rested on each of them. All of them were filled with the Holy Spirit, and began to speak in other languages”. The Word of God, the Pope points out, describes the action of the Spirit, who " first he rests on each and then brings all of them together in fellowship. To each he gives a gift, and then gathers them all into unity". In other words, the same Spirit creates diversity and unity, and in this way forms a new, diverse and unified people: the universal Church" First, " in a way both creative and unexpected, he generates diversity, for in every age he causes new and varied charisms to blossom." Then the same Spirit " brings about unity: he joins together, gathers and restores harmony. In fact, the Pope continues by quoting the commentary on the Gospel of John of Cyril of Alexandria, "By his presence and his activity, the Spirit draws into unity spirits that are distinct and separate among themselves." He does so in a way that effects "true union, according to God’s will, a union that is not uniformity, but unity in difference."

For this to happen "we need to avoid two recurrent temptations ". The first, Francis warns, is to "seek diversity without unity". This happens when " want to separate, when we take sides and form parties, when we adopt rigid and airtight positions, when we become locked into our own ideas and ways of doing things, perhaps even thinking that we are better than others, or always in the right" then " we choose the part over the whole, belonging to this or that group before belonging to the Church. We become avid supporters for one side, rather than brothers and sisters in the one Spirit. We become Christians of the “right” or the “left”, before being on the side of Jesus, unbending guardians of the past or the avant-garde of the future before being humble and grateful children of the Church." The result is "diversity without unity".
The opposite temptation is that of "seeking unity without diversity". In this way "unity becomes uniformity, where everyone has to do everything together and in the same way, always thinking alike. Unity ends up being homogeneity and no longer freedom. But, as Saint Paul says, “where the Spirit of the Lord is, there is freedom". Therefore, the Pontiff goes on, " the prayer we make to the Holy Spirit is for the grace to receive his unity, a glance that, leaving personal preferences aside, embraces and loves his Church, our Church. It is to accept responsibility for unity among all, to wipe out the gossip that sows the darnel of discord and the poison of envy, since to be men and women of the Church means being men and women of communion. It is also to ask for a heart that feels that the Church is our Mother and our home, an open and welcoming home where the manifold joy of the Holy Spirit is shared."

There is then the "second new thing brought by the Spirit: a new heart ". The Risen Jesus, appearing for the first time to his disciples, says, "Receive the Holy Spirit. If you forgive the sins of any, they are forgiven them" Jesus, Bergoglio says, "does not condemn them for having denied and abandoned him during his passion, but instead grants them the spirit of forgiveness. The Spirit is the first gift of the risen Lord, and is given above all for the forgiveness of sins" Here we see " the beginning of the Church, the glue that holds us together, the cement that binds the bricks of the house: forgiveness". Because “forgiveness is gift to the highest degree; it is the greatest love of all. It preserves unity despite everything, prevents collapse, and consolidates and strengthens. Forgiveness sets our hearts free and enables us to start afresh. Forgiveness gives hope; without forgiveness, the Church is not built up.”

The spirit of forgiveness resolves everything in harmony, and leads us to reject every other way: the way of hasty judgement, the cul-de-sac of closing every door, the one-way street criticizing others. Instead, the Spirit bids us take the two-way street of forgiveness received and given, of divine mercy that becomes love of neighbor, of charity as “the sole criterion by which everything must be done or not done, changed or not changed”.

Particularly severe security measures have been deployed throughout the area around the Vatican. Barriers and controls were set up by law enforcement officers along the access roads. The pilgrims were driven along compulsory routes and had their bags and backpacks checked before entering the square through a metal detector.

At the end of the Mass on Pentecost, the Pope recited the Regina Coeli invoking the Holy Spirit to "grant peace to the whole world and heal the wounds of war and of terrorism, which even this [Saturday] night, in London, struck innocent civilians: let us pray for the victims and their families". The Pontiff then recalled his message for the next World Mission Day celebrated each year in October. The theme is: The mission at the heart of the Christian faith. "The Holy Spirit supports the mission of the Church in the whole world and strengthens all missionaries of the Gospel," the Pope said, who then greeted and invited "pilgrims from Italy and many parts of the world to participate in this celebration". In particular, the Pontiff addressed the "Catholic Charismatic Renewal Groups, celebrating their 50th foundation, and also the brothers and sisters of other Christian confessions that join our prayer." He then turned to the "Daughters of Mary Help of the Latin Americans" and thanked the choir and the orchestra of Carpi's children that "performed some songs during Mass in collaboration with the Sistine Chapel". Francis finally concluded calling for the motherly intercession of the Virgin Mary, "May she obtain for us renewed zeal in bringing to everyone the Good News of the life that is victorious over death".