Iconoclasm: Literally, “destruction of images.” Historically, iconoclasm arose in the eighth century as the practice of destroying images (icons) of Jesus Christ often found in the gathering places of certain Christian churches. Many Christians worshiped the icons as representations of Jesus Christ in his physical incarnation. The iconoclastic controversy began in A.D. 725 when Emperor Leo III decided to have icons destroyed because he thought icon worship was idolatrous and a hindrance to the conversion of Jews and Muslims.
Stanley J. Grenz;David Guretzki;Cherith Fee Nordling. Pocket Dictionary of Theological Terms (Kindle Locations 677-680). Kindle Edition.
Docetism: A term used to refer to a theological perspective among some in the early church who regarded the sufferings and the human aspects of Christ as imaginary or apparent instead of being part of a real incarnation. The basic thesis of such docetics was that if Christ suffered he was not divine, and if he was God he could not suffer. The combination of the two natures, Son of David, and Son of God, affirmed by Paul in Rom. 1:3-4 was apparently already under attack in the Johannine community (see 1John 4:2; 2John 7)). Dosetic thinking became an integral part of the perspective of Gnostics, who viewed Jesus as the alien messenger from outside the present evil world and one who was untouched by the evil creator. This alien Jesus came to awaken Gnostics to their destiny outside the realm of creation. While the framers of the Apostle’s and Nicene Creeds, were opposed to docetic teaching and clearly assumed the two natures of Jesus, the drafters of the Definition of Chalcedon (AD 451) made explicit the Christian teaching concerning Jesus Christ as “truly God and truly man.”
 Elwell, Walter A. Evangelical dictionary of theology (Grand Rapids, Mich.: Baker Book House, 1984), 326. Print..