What is the ruling on one who mocks the Prophet (peace be upon him) or claims to have a better understanding than him, or believes that the beard is a source of dirt, and do they commit an act of disbelief by doing so?

Mocking Allah, His verses, or His Messenger is major disbelief that expels one from the faith, whether done seriously or in jest. Whoever describes himself as more understanding than the Prophet, peace be upon him, in matters of religion commits major disbelief. However, in worldly matters, it is not disbelief unless it involves belittlement.

The statement that if the Prophet, peace be upon him, were alive today, he would own the most luxurious cars and the most wealth, is a baseless conjecture and ignorance of his life, which was characterized by asceticism. Letting the beard grow is obligatory according to the majority of scholars and is one of the acts of fitra (natural disposition). Whoever describes it as dirty is either ignorant or mocking an Islamic ritual.

A Muslim should learn matters of their religion from authentic sources and stay away from orientalists' books which contain erroneous ideas. An ignorant Muslim is better than one who has been influenced by these ideas. It is recommended to arm oneself with religious knowledge to repel doubts and avoid delving into declaring people disbelievers.