Where did she say that, and what, exactly, did she say?
Many times she talked about Christ not being the only route to heaven. And now we know why. She didn't have much of a clue as to which road to really take. Obviously, her lack of true faith and trust in God's word permitted her to embrace so much error...
A first-up from google...
In 184 pages, there was nothing stating that salvation was through Jesus alone. She wrote, "I've always said we should help a Hindu become a better Hindu, a Muslim become a better Muslim, a Catholic become a better Catholic" (p. 31). There is no attempt to let others know that Jesus is the only way. There is no hint that "Mother" Teresa or her "sisters" believed the narrow way Jesus preached (cf. Matt. 7:13-14)... In 12/96, a former nun in "Mother" Teresa's order wrote the following letter (Source: FBIS, 2/1/97):
"But my main worry was the corporal penances used by the sisters and kept in small hand-made drawstring bags, along with toothbrush, needle and thread, etc. These include a whip made of rope and bracelets and waist-chains made of something similar to gardening wire which pierce the flesh. These penance implements are made by the novices in Rome. This is dangerous to the health, but is kept secret." (Signed, Pamela Hursch, England).""I love all religions. ... If people become better Hindus, better Muslims, better Buddhists by our acts of love, then there is something else growing there." [On another occasion, she again demonstrated her false gospel that 'there are many ways to God': "All is God -- Buddhists, Hindus, Christians, etc., all have access to the same God."]...
"I myself was in Mother Teresa's order, the Missionaries of Charity. I am now a Christian. I was saved on 3/3/96 ... You are quite right about the pagan influences on the order. When I was a postulant in Rome, we had Hindu-style meditation techniques from a book called "Sadhana" by Father Antony De Mello. Mother Teresa behaves like a Hindu guru. She visits each convent at six monthly to yearly intervals. The sisters seem to live for these visits and sit worshipfully at her feet when she gives one of her talks. On the special occasion when she presented us with our personal rosaries (in the postulancy in Rome) she said, "My words are scripture for you," and of course she was right. All the letters which she writes on "spiritual" matters are kept, printed and copied and bound into volumes. Each convent has a copy of these volumes of her words which are studied daily as Christians study the Bible. Cuttings of Mother Teresa's hair and pieces of her saris are kept in a cupboard in Rome, ready to be made into relics when she is canonized.
From a "Catholic" Source:
“I’ve always said we should help a Hindu become a better Hindu, a Muslim become a better Muslim, a Catholic become a better Catholic.”
“Some call Him Ishwar, some call Him Allah, some simply God, but we have to acknowledge that it is He who made us for greater things: to love and be loved. What matters is that we love. We cannot love without prayer, and so whatever religion we are, we must pray together.”