In a recent answer to a question, Michelle Arnold said that Buddhism was incompatible with Catholicism. Does she mean that it is completely incompatible so that we must reject things like fasting, celibate monastaries, and respect for authority? If we do not reject them because they are found in Buddhism but because the reason they do those things is bad, how is that different from saying “faith alone” saves?
Your question presumes that the Church received “fasting, celibate monastaries, and respect for authority” from Buddhism and so cannot reject Buddhism without also rejecting these goods. Since the Church had all of these things long before Christians ever met Buddhists, then the relationship is obviously not interdependent. The Church recognizes that Buddhism contains some truth (cf. Nostra Aetate 2), but it does not accept a false syncretism that presumes that Catholicism and Buddhism are compatible in such a manner that Catholics can remain or become Buddhists.