From the Humanist Manifesto
There is great danger of a final, and we believe fatal, identification of the word religion with doctrines and methods which have lost their significance and which are powerless to solve the problem of human living in the Twentieth Century. Religions have always been means for realizing the highest values of life. Their end has been accomplished through the interpretation of the total environing situation (theology or world view), the sense of values resulting therefrom (goal or ideal), and the technique (cult), established for realizing the satisfactory life. A change in any of these factors results in alteration of the outward forms of religion. This fact explains the changefulness of religions through the centuries. But through all changes religion itself remains constant in its quest for abiding values, an inseparable feature of human life.
Many Christians would say that Christianity is not a religion, it is a relationship with Jesus Christ. An honest person would recognize many of the similarities between Christianity and other religions. Christianity is a set of beliefs and practices. I think what these Christians are trying so say is that other religions are false and theirs is the one true religion.