The Quran, like all previous scriptures, delivers the one and only message of God to mankind, worship God alone and follow God alone.
God describes the Quran as a beacon to guide, warn, and bring good news. It is also a statute book with set laws and systems for mankind. As mentioned in the following verses:
Surah 16 Verse 102
Say: The holy Spirit hath delivered it from thy Lord with truth, that it may confirm (the faith of) those who believe, and as guidance and good tidings for those who have surrendered (to Allah).