VATICAN CITY (Reuters) - Pope Francis, speaking to an overflow crowd of more than 150,000 in St Peter's Square, urged the world on Sunday to be more forgiving and merciful and not so quick to condemn other people's failures.
"A little bit of mercy makes the world less cold and more just," he told the cheering crowd from the window of the papal apartments overlooking the square.
Four days after his election, the former Cardinal Jorge Bergoglio of Argentina spoke both as pope and as parish priest -earlier he said Mass for a few hundred Vatican workers in a tiny church just inside the city-state's walls.
Chants of "Francesco, Francesco, Francesco," the pope's name in Italian, reverberated through the square and down a long boulevard leading to the Tiber River.
Since his election on Wednesday as the first non-European pope in nearly 1,300 years, Francis has signaled a sharp change of style from his more aloof predecessor, Benedict, and laid out a clear moral path for the 1.2-billion-member Church, which is beset by scandals, intrigue and strife.
"Brothers and sisters, good morning," he said, using a familiar style that has already become his hallmark.
He wove his address from the window as well as his earlier homily around the Gospel story of the crowd that wanted to stone a woman who had committed adultery but was saved by Jesus.
Jesus told them "let he among you who is without sin, cast the first stone" and then told the woman "go and sin no more".
"I think even we are sometimes like these people, who on the one hand want to listen to Jesus, but on the other hand, sometimes we like to stone others and condemn others. The message of Jesus is this: mercy," he said at the morning Mass.
"I came because I love this pope," said Anna Barone, an elderly woman from southern Italy as she craned her neck to get a glimpse of him.
"I hope this means a better future for the Church. He seems to have good intentions. I hope they let him make changes. The Church must be poor in spirit, not just in material goods. It has to get closer to the people. I am very hopeful," she said.
In a sign of appreciation that he had taken his name from St. Francis of Assisi, who preached to animals and defended nature, a group held up a banner reading: "Animal lovers and animals thank the pope".
In both his address and homily, the pope said people should be open to God's mercy, even those who have committed grave sins.
"The Lord never tires of forgiving, never! It is we who tire of asking for forgiveness," he said at the Mass.
The crowd in the square laughed when he mentioned a book by German Cardinal Walter Kasper.
"I liked that book a lot but don't think I am trying to advertise books by my cardinals," he said.
Before he entered the tiny church of Santa Anna for the morning Mass, Francis stopped to greet well-wishers who had lined up outside a nearby Vatican gate.
He chatted and laughed with many of them before pointing to his black plastic wrist watch and saying: "It's almost 10 o'clock. I have to go inside to say Mass. They are waiting for me."
Inside, he wore the purple vestments of the liturgical season of Lent, which ends in two weeks on Easter Sunday.
At the end of the Mass, he waited outside the church and greeted people as they left the building, like a parish priest, asking many of them: "Pray for me".
His last words before he left the window were: "Have a nice Sunday and have a nice lunch".
Editing by Sonya Hepinstall