[Longshanks]

Thank you for including the modern Catholic Church among validly Christian denominations but your answer requires me to repose the question. If Rome strayed, then when and by what specific actions did this occur and who, by contrast, made up the non-straying portion of the church.

[meandog]

If Rome strayed, then when and by what specific actions did this occur and who, by contrast, made up the non-straying portion of the church.

(strayed)...all within recent history: (in 1854 and 1950 by popes who declared the Virgin Mary to be Immaculately Conceived and Assumed Bodily into heaven respectively) and (in 1870) when Vatican Council I declared the pope "endowed with infalibility, ex cathedra"... (not strayed) the Eastern Rite and Eastern Orthodoxy of the church--i.e. priests allowed to marry.