When John Paul beatified Mother Teresa of Calcutta in 2003, he said of her, in part:

Blessed Mother Teresa of Calcutta.jpg“As you did to one of the least of these my brethren,
you did it to me” (Mt 25: 40). This Gospel passage, so crucial in
understanding Mother Teresa’s service to the poor, was the basis of her
faith-filled conviction that in touching the broken bodies of the poor she was
touching the body of Christ. It was to Jesus himself, hidden under the
distressing disguise of the poorest of the poor, that her service was directed.
Mother Teresa highlights the deepest meaning of service – an act of love done
to the hungry, thirsty, strangers, naked, sick, prisoners (cf. Mt 25: 34-36)
is done to Jesus himself

Recognizing him, she ministered to him with
wholehearted devotion, expressing the delicacy of her spousal love. Thus, in
total gift of herself to God and neighbor, Mother Teresa found her greatest
fulfillment and lived the noblest qualities of her femininity. She wanted to be
a sign of “God’s love, God’s presence and God’s compassion,” and so remind all
of the value and dignity of each of God’s children, “created to love and be
loved.” Thus was Mother Teresa “bringing souls to God and God to souls” and
satiating Christ’s thirst, especially for those most in need, those whose
vision of God had been dimmed by suffering and pain.