Our true identity cannot be lived out in glum negativity, but only in the knowledge that, in God's eyes, our value cannot be measured; no one is insignificant.

Pope Francis made these remarks on Sunday to at least 1.5 million young people gathered in Krakow for the final Mass of World Youth Day (WYD).

"God loves us the way we are, and no sin, fault or mistake of ours makes him change his mind," the Pope said in his homily to the crowds of young people who filled Polish city's "Campus Misericordiae" – or "Field of Mercy."

"No one is insignificant," the pontiff said. "He loves all of us with a special love; for him all of us are important: you are important!"

"In his eyes, you are precious, and your value is inestimable."

In contrast, to not "accept ourselves, to live glumly, to be negative, means not to recognize our deepest identity," he said. "It is like walking away when God wants to look at me, trying to spoil his dream for me,"

Sunday's Mass was the final major event of WYD in Krakow, and marks the end of the Pope's July 27-31 visit to Poland.

Pope Francis centered his address on the day's Gospel account of Jesus' encounter with the tax collector Zacchaeus, a man despised by the Jews for his collaboration with the Romans.

The scene demonstrates how Jesus does not simply want to "greet" people, the Pope said. Rather, he "wants to draw near to us personally, to accompany our journey to its end, so that his life and our life can truly meet."

There were several key obstacles which Zacchaeus had to overcome in approaching Jesus, the pontiff explained, the first his being so physically small that he had difficulty seeing Jesus in the crowd.

"Even today we can risk not getting close to Jesus because we don't feel big enough, because we don't think ourselves worthy," the Pope said. "This is a great temptation; it has to do not only with self-esteem, but with faith itself."

"We have been created in God's own image; Jesus has taken upon himself our humanity and his heart will never be separated from us; the Holy Spirit wants to dwell within us. We have been called to be happy for ever with God!"

Francis explained that our true "stature" is found in our spiritual identity: that is, in the fact that we "are God's beloved children, always."

"Not to accept ourselves, to live glumly, to be negative, means not to recognize our deepest identity," he said. "It is like walking away when God wants to look at me, trying to spoil his dream for me."

The Pope added that "God loves us the way we are, and no sin, fault or mistake of ours makes him change his mind."

"No one is insignificant. He loves all of us with a special love; for him all of us are important: you are important!"

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God is not concerned about whether you are stylish or what kind of phone you have, Pope Francis said. "In his eyes, you are precious, and your value is inestimable."

"He believes in us even more than we believe in ourselves. He is always "cheering us on"; he is our biggest fan."

However, to brood over our problems or "past injuries," the pontiff said, "is unworthy of our spiritual stature!"

"It is a kind of virus infecting and blocking everything; it closes doors and prevents us from getting up and starting over. God, on the other hand, is hopelessly hopeful!"

Francis encouraged the youth in their awareness of being God's beloved sons and daughters, end recommended that they pray every morning: "Lord, I thank you for loving me; help me to be in love with my own life!"

Another obstacle Zacchaeus faced was his shame before Jesus. "It must have been quite a struggle – on one hand, a healthy curiosity and desire to know Jesus; on the other, the risk of appearing completely ridiculous."

However, the "attraction of Jesus was more powerful" than Zacchaeus' shame, the Pope said, comparing his encounter to that of someone who behaves in unexpected ways upon falling in love.

"For us too, this is the secret of joy: not to stifle a healthy curiosity, but to take a risk, because life is not meant to be tucked away," he said.

However, Francis explained we cannot wait around when Jesus "offers us life – we can't respond by thinking about it or 'texting' a few words!"

The Pope went on to encourage young people to not be ashamed of bringing everything to the sacrament of confession, "especially your weaknesses, your struggles and your sins."

"He will surprise you with his forgiveness and his peace," he said.

Pope Francis challenged young people to not let their "soul become numb," but to say without fear "yes" to Jesus, aiming for "the goal of a beautiful love which also demands sacrifice."

Finally, the third obstacle which  Zacchaeus faced came from the crowds, their judgment of him on account of his profession, and of Jesus for his willingness to enter the house of a sinner.

"People will try to block you, to make you think that God is distant, rigid and insensitive, good to the good and bad to the bad," he said.

Instead, Jesus "demands of us real courage: the courage to be more powerful than evil by loving everyone, even our enemies."

Although people may laugh at you, or judge you for being dreamers, "do not be afraid," Pope Francis said. "Don't be discouraged: with a smile and open arms, you proclaim hope and you are a blessing for our one human family, which here you represent so beautifully!

Unlike the crowds who looked on Zacchaeus with judgement , Jesus "gazed up at him," the Pope said.

"Jesus looks beyond the faults and sees the person," and sees the "future good," he said. This "gaze remains constant, even when it is not met; it seeks the way of unity and communion.

Pope Francis said WYD begins today, but "continues tomorrow, in your homes, since that is where Jesus wants to meet you from now on."

God does not want young people to remain in the beautiful city of Krakow or in their "cherished memories" of the place.

Rather, "he wants to enter your homes, to dwell in your daily lives: in your studies, your first years of work, your friendships and affections, your hopes and dreams."

"How greatly he desires that you bring all this to him in prayer!"

Francis reminded young people that Jesus calls them by name, as he did Zacchaeus. "Your name is precious to him," he said.

"May we too now try to imitate the faithful memory of God and treasure the good things we have received in these days," the Pope concluded.  

"In silence, let us remember this encounter, let us preserve the memory of the presence of God and his word, and let us listen once more to the voice of Jesus as he calls us by name."