Is it a condition for converting to Islam to pronounce the Two Testimonies in front of two Muslim witnesses?

Entry into Islam is achieved by uttering the two testimonies (Shahadatayn), and it is not a condition to have witnesses for this; merely uttering them is sufficient. The Messenger of Allah, peace and blessings be upon him, made entry into Paradise conditional upon uttering the two testimonies, as in his saying: "Whoever says: 'I bear witness that there is no god but Allah, alone, without partner, and that Muhammad is His servant and Messenger, and that Jesus is the servant of Allah and the son of His maidservant and His word which He bestowed upon Mary and a spirit from Him, and that Paradise is true, and that the Fire is true,' Allah will admit him to Paradise through whichever of the eight gates he wishes." Narrated by Muslim. The Quran also indicates the validity of the covenant of Islam for one who conceals his Islam and is not witnessed, as in His (Allah's) saying: {And if there had not been believing men and believing women whom you did not know – that you might trample them, and there would strike you on account of them unintended harm…} [Al-Fath: 25].

The meaning of the two testimonies must be understood: "I bear witness" means I believe with firm conviction. "There is no god but Allah" means there is no deity worthy of worship except Allah. "Muhammad is the Messenger of Allah" means there is no leader to be rightfully followed except Muhammad, peace and blessings be upon him, for he is the sole intermediary between Allah and His creation, and Allah's law is known through him. Any deviation from his guidance is a rejected innovation. Uttering the two testimonies entails submission to Allah's command and adherence to His law.