The most accurate summary of the fundamental beliefs of Islam and its religious practices, based on the provided quote from the Quran, is:
"The Quran is a sacred scripture and teachings that all Muslims follow. The primary-source scripture is the first pillar: profession of faith."
This response reflects the core belief in the oneness of God and the prophethood of Muhammad, which is encapsulated in the Shahada, the first pillar of Islam.