Why must a Muslim associate the name of the Prophet Muhammad, peace be upon him, with the name of Allah, Almighty and Majestic, in the Shahada, even though we know that the hypocrites testify: "Indeed, you are the Messenger of Allah," and Allah knows that they are liars?

A person's entry into Islam requires uttering the two testimonies (Shahadatayn): "There is no deity worthy of worship but Allah, and Muhammad is the Messenger of Allah," along with firm belief in their implications and acting upon them. Neither of these testimonies suffices without the other. The Prophet (peace be upon him) clarified Islam through this, and he commanded fighting people until they testify to both. Allah Almighty's saying: ﴿Indeed, the believers are those who have believed in Allah and His Messenger﴾ [An-Nur:62] confirms that belief in the Messenger is a condition for the validity of Islam. As for the hypocrites, their statement "We testify that you are indeed the Messenger of Allah" is a verbal utterance without heartfelt belief; they are lying in this testimony. They declare Islam while concealing disbelief, and this is what verses like Allah Almighty's saying mean: ﴿When the hypocrites come to you, they say, "We testify that you are indeed the Messenger of Allah." And Allah knows that you are His Messenger, and Allah testifies that the hypocrites are liars﴾ [Al-Munafiqun:1].