Islam, the Spirit and the essence of religion in the Quran

Does religion have a body and spirit, kernel and skin or perhaps nature and essence? If so, what is the spirit, the kernel and the essence of religion in the Holy Qur'an? this article is focused on the fact that the spirit and essence of religion in the Holy Quran is "Islam"; that is, surrendering to the truth. Accordingly, the purpose of religion is to breed people of this kind. The Holy Quran uses determinative denomination to name the religion it calls people to as "Islam". All Prophets were Muslim and they invited people to Islam. Islam is the only accepted religion to God and nobody is excused if he follows any religion other than Islam. The criterion to categorize religions in Quran is breeding humans submissive to right. This implies that the spirit and the essence of religion in the Quran is "Islam", that is, to be surrendered to the truth.