The idea that Prophet Muhammad (peace be upon him) wrote the Quran is a prevalent one in the West. Even those who are sympathetic to Islam among western writers cannot admit that the Quran is a revelation from God.
Prophet Muhammad, peace be upon him, said: "Whoever is kind, Allah will be kind to him; therefore be kind to man on the earth and He Who is in heaven will show mercy on you."(Abu Dawud & Tirmidhi)