Pope Francis was serenaded by Aretha Franklin at the Festival of Families in Philadelphia in front of hundreds of thousands of people. The Pontiff smiled as the Queen of Soul sang Amazing Grace with the backing of a gospel choir in front of the largest crowds Francis has seen so far on his six-day tour of the US.

The 73-year-old singer belted out the high notes to the hit song while the Pope watched on.

Not for the first time, the Pope took time out of his packed schedule to bless a disabled man, beaming as he talked to an ecstatic Ukrainian teenager with cerebral palsy.

Pope Francis was honored in front of a crowd of over 300,000 people at the Festival of Families hosted by Mark Wahlberg.

The message of the night focused on the importance of family, with Pope Francis telling the enthusiastic crowd, “In the family, there are difficulties, but those difficulties are overcome with love. Love is about celebration, love is joy, love is moving forward.”

He said families must take care of grandparents and children, but, showing a sign of his wicked sense of humor, said that he would not speak about mother-in-laws.

The Pope was joined on stage by families from the US, Australia, Ukraine, Jordan, Nigeria, and his homeland of Argentina.

The first to meet him were engaged Australian couple Camilius O'Kane and Kelly Walsh, they asked about gay marriage, voicing their concerns about 'the push to change the legal definition of marriage.'

Ukrainian Lesya Boris and her son Bogdan, who has cerebral palsy, also met the Pope, who spent time talking to them as he has with several disabled children during his tour of the US.

There was a touching moment as young choirboy Bobby Hill took to the stage, singing perfect falsetto and winning over the Pope and the crowd. Francis beamed as he chatted to the boy, who hugged Mark Wahlberg after the performance.

Aretha Franklin then took to the stage to sing Amazing Grace, drawing cheers from the crowd and polite applause from Francis.