Complex sentence: Even though the Prophet Muhammad had no authority to change the Qur'an, he was active in the way that he received the revelations in full consciousness, witnessing in his heart the greatness of the presence of the voice of God.
Split into simpler sentences: Even though the Prophet Muhammad had no authority to change the Qur'an he was not a passive bystander. He was active in the way that he received the revelations in full consciousness, witnessing in his heart the greatness of the presence of the voice of God.