Re: Greeting others with Merry Christmas…
Ameen … We also need to go leniently on our fellow Muslims and make excuses for them, more so in this day and age. If we can stand clear from the boundaries we are safe, but if others are closer to those boundaries and say their intentions are pure - then we should not hold them to account. It is also clear that the ruling is one based on “consensus of scholars” which is a valid basis for something to be forbidden, it is not from Qur’an or hadith directly, and as long as they have even a few of the more lenient fatwas I believe they are safe too. But if you can be more prudent yourself then do so … and may Allah (SWT) reward you accordingly.
Also note that the response given by Dr. Phillips that you posted referring to Ibn-ul-Qayyim regarding the matter of returning festive greetings - Ibn-ul-Qayyim did also state “even if you are saved from shirk” …
I believe shirk has to be with intent to be shirk. But not all forbidden acts must be with intent to be forbidden. And if there is consensus in a matter with the scholars for it to be forbidden then this is acceptable, but deeming anything forbidden and there being no consensus on it while it is in no clear terms in the scriptures then this is dangerous and is itself a biddah.
GF Haddad and an opinion I follow - do not call celebrations of mawlid (birthdays) reprehensible biddah and we are from a school that distinguish biddah hasana from biddah sayyiah