Ishmael's paradox

A fundamental question I am avoiding at the moment is the role that Christian thought has played in shaping a modern relativist attitude (and I would like to read something on this subject).

In a nice passage of Moby Dick, Ishmael ponders if joining Queequeg in his prayers, at risk of committing idolatry. According to him, sometimes a good Christian must turn idolator.
Ishmael's relativist argument is evidently paradoxical, but it seems to me that the Christian principle on which it is based ("to do to my fellow man what I would have my fellow man to do to me") invites paradox.

...I was a good Christian; born and bred in the bosom of the infallible Presbyterian Church. How then could I unite with this wild idolator in worshipping his piece of wood? But what is worship? Thought I. Do you suppose now, Ishmael, that the magnanimous God of heaven and earth--pagans and all included--can possibly be jealous of an insignificant bit of black wood? Impossible! But what is worship?--to do the will of God--THAT is worship. And what is the will of God?--to do to my fellow man what I would have my fellow man to do to me--THAT is the will of God. Now, Queequeg is my fellow man. And what do I wish that this Queequeg would do to me? Why, unite with me in my particular Presbyterian form of worship. Consequently, I must then unite with him in his; ergo, I must turn idolator...
[Moby Dick, chapter 10]