Was the answer correct that faith's place is the heart, but one must follow the Quran and Sunnah by growing a beard to revive the Prophetic Sunnah? And what is advised as a response to those who criticize growing a beard?

Your reply to the person is correct regarding the obligation to obey the commands of Allah and His Messenger (peace be upon him), and that growing the beard is one of them. However, your reply was deficient in its affirmation that faith resides in the heart and not in the beard. This is a phrase some people use to evade religious obligations.

This statement can be refuted by the fact that, according to Ahl al-Sunnah, faith is composed of speech, belief, and action, and actions are a part of faith. Moreover, Allah has made the actions of the limbs a confirmation and proof of what is in the hearts. Thus, love is demonstrated by following the Messenger (peace be upon him). It is not possible to reconcile firm faith with a lack of obedience to the commands of Allah and His Messenger, for one who loves obeys the beloved.