I agree that elements of the Truth are found outside of the visible boundaries of the Roman Catholic Communion.  I also agree that the graces of salvation are found outside of the visible boundaries of the Roman Catholic Communion.  

That, however does not mean that Truth is relative, or that all religions are equally valid expressions of Truth.

I also fail to understand why you are even bringing this up, because I don't see what it has to do with the Sacrament of Baptism.