this is what happens when we live among the goyim, racchmana ltzon
we are swept away by their values and mix them in with Hashem’s values, without even realizing it
then we rationalize it with sources, like the missionaries do.
this is one of the prime reasons, according to Rabbi Miller, tzl, for the chok of Shaatnez.(as stated in Medresh Tanchuma, as i recall). Kayin brought linen, Hevel brought wool. a reminder that we should not mix the pure (intentions in this case) with the impure
one day our hearts will be purified from this filth