We are trying to convince everyone that the devotional service of the Lord is enjoined in every scripture. If a person is religious, he must accept the supreme authority of the Lord, become His devotee and try to love Him. This is the real principle of religion. It does not matter whether one is Christian, Muslim, or whatever. He simply must accept the sublime position of the Supreme Personality of Godhead and render service unto Him. It is not a question of being Christian, Muslim, or Hindu. One should be purely religious and freed from all these material designations. In this way one can learn the art of devotional service. This argument appeals to all intelligent men.

Srila Prabhupada; Cc 2.25.20, purport