Encratites
Titian wrote a harmony of the gospels called the Diatessaron. Later he became very violent and apostatized from the church and founded the Gnostic sect of the Encratites. He then started removing passages from the Diatessaron that refer to Jesus divinity and other non-Gnostic thoughts. Copies of the original and the perverted are still existent. The eastern church used the Diatessaron for years before going back to the four gospels. The basic teachings of the Encratites are:

• Irenaeus 178 AD
• Against Heresies 3.11 - The Encratitae who, on account of such as come in hypocrisy, hold themselves aloof from the communion of the brethren. 
• Against Heresies 3.23 - Adam was saved, contrary to Tatian. There was no way possible for Adam to become a god.
   
• Clement of Alexandria 192-202 
• Instructor 2.2 - We use water mixed with wine for communion, and the wine is just a symbol of the blood of Jesus, but it does sanctify both body and soul to those who take it in faith. We are to be careful of drunkenness, but avoid any, who like the Encratites, teach drinking wine is a sin.
   
• Hippolytus 170-236 AD
• Refutation of all Heresies 8.13 Encratites are very prideful and violent, abstaining from animal food, (and) being water-drinkers [used water instead of wine for communion], and forbidding to marry, and devoting themselves to asceticism.
  

Tatian 166AD
Tatian started off orthodox. By the time he wrote his book To the Greeks he was beginning to go Gnostic. We see he was orthodox in the following:

• Greeks 4 - There is only one God
• Greeks 5 - God and the Logos created the world, not the angels. Matter is not self-existent.
• Greeks 6 - We did not exist before we were born and do not reincarnate. There will be a physical resurrection.
• Greeks 7 -  Jesus created men and angels with free will. Jesus had foreknowledge of what free agents would do. There is no such thing as fate.
• Greeks 9 - Demons invented the concept of fate with astrology to enslave man into worshiping them.
• Greeks 11 - Our free will enslaved us to sin. (Rom 7) but we can choose to follow righteousness now.
• Greeks 17 - Demons use numbers, letters, roots, and amulets to ensnare people.
• Greeks 21 - Jesus was God born in the form of man.
• Greeks 25 - God the Father does not have a physical body.
• Greeks 26 - Christians do not eat human flesh (as it has been rumored)
• Greeks 32 - Women and children of any age who want to hear are allowed to attend church.
• Greeks 38 - Moses is named in Egyptian history.
   
• But also taught the following Gnostic ideas:
• Greeks 13 - The soul is not eternal, it dissolves with the body, but will be brought back at the resurrection.
• Greeks 18 - Demons use medicine also (He does not believe in taking medicine. We should rely on God alone.)

After this Tatian becomes very violent and he secedes from the church forming the Gnostic Encratites. The name in Greek means self-perfected ones. In the 12th century the name of Encratites was applied to the Bogomils.

References:

Irenaeus Against Heresies 1.28 Hippolytus Against Heresies 8.13

Origen Cel. 5.65