"In every system of religion, it is accepted that God is the supreme father of all living entities. According to Christianity, the supreme father, God, provides the living entities with all of life's necessities. Therefore they pray, "Give us this day our daily bread." Any religion that does not accept the Supreme Lord as the absolute father is called kaitava-dharma, or a cheating religion. Such religious systems are rejected in Srimad-Bhagavatam (1.1.2): dharmah projjhita-kaitavo 'tra. Only an atheist does not accept the omnipotent supreme father. If one accepts the omnipotent supreme father, he abides by His orders and becomes a religious person."
Caitanya-caritamrta, Madyam lila 20:275
"This is the position. We are many, and God is one. So if we accept one God, then where is the chance of different religious system? God is one. God is neither Christian nor Hindu or Muslim or... No. God is God. Just like gold. Gold is gold. Either in the Hindu community, or Muslim community, gold is gold. Because gold is there in some Hindu community, nobody says "Hindu gold." Does anybody say, "It is Hindu gold" or "It is Christian gold"? No. Gold is gold. Similarly, God is one. There is no "Hindu God" or "Muslim God" or "Christian God." This is mistake. "We believe God in this way...," that is nonsense. No. God is one, and you have to see what is the characteristic of God. ...That should be the subject matter of theology, to know actually what is God and to understand what is our relationship with God."
Srila Prabhupada Lecture, 06-26-75, Los Angeles
"...In perfect human society everyone should engage in the devotional service of the Lord. It does not matter whether one is born poor or rich, black or white. There may be so many material distinctions for one who takes birth in human society, but everyone should engage in the Lord's devotional service. At the present moment civilized nations have given up God consciousness for economic development. They are actually no longer interested in advancing in God consciousness. Formerly their forefathers were engaged in executing religious principles. Whether one is Hindu, Muslim, Buddhist, Jewish or whatever, everyone has some religious institution. Real religion, however, means becoming God conscious."
"God's service is dharma. This dharma may be described differently in different countries according to different cultural and climatic conditions or situations, but in every religious scripture obedience to God is instructed. No scripture says that there is no God or that we as living entities are independent-- not the Bible, the Koran, the Vedas or even the Buddhist literatures. ...We may accept Krsna, or Lord Jesus Christ, or Jehovah, or Lord Buddha, or Sankaracarya, or Guru Nanak, but in any case acceptance of authority is required."
Elevation to Krsna Consciousness, Chapter 6
"Dharma cannot be changed. Therefore we must find out what is our dharma, what is our religion. ...we are professing that "Christianity is my religion," "Hinduism, my religion," that is not religion. That is faith. Religion is different. Religion you cannot change."
Srila Prabhupada Lecture, 11-04-66 (Gaura Purnima), New York
"When we are on the material platform, there are different types of religions -- Hinduism, Christianity, Mohammedanism, Buddhism, and so on. These are instituted for a particular time, a particular country or a particular person. Consequently there are differences. Christian principles are different from Hindu principles, and Hindu principles are different from Mohammedan and Buddhist principles. These may be considered on the material platform, but when we come to the platform of transcendental devotional service, there are no such considerations. The transcendental service of the Lord (sadhana-bhakti) is above these principles. The world is anxious for religious unity, and that common platform can be achieved in transcendental devotional service. This is the verdict of Sri Caitanya Mahaprabhu. When one becomes a Vaisnava, he becomes transcendental to all these limited considerations."
Caitanya-caritamrta, Madyam lila 25:121
Bhaktivedanta Book Trust. HDG A.C. Bhaktivedanta Swami Srila Prabhupada.