This book is directed to the Christians to contemplate about the truth about Jesus peace be upon him in order to know him clearly. And they should not follow the teaching of the church blindly that leads them to the misguidance in this life and to the eternal lose in the Hereafter. It clarifies that Jesus peace be upon him is God's slave and messenger who worshiped non but God and ordered his followers to worship non but God Who has the wright to be worshiped without any partner. Also this book nullified the doctrines of Christianity such as the divinity of Jesus, incarnation, crucifixion and redemption because they are not logical and contradict their scriptures. They were innovated and obligated on people by force by the power of the church and Roman emperors. They were nullified with evidences from the Bible, the history of Christians and their scholars. Introduce this book "O Christians Know Jesus" to the Christians, the people of thought to contemplate.