Apollinarianism developed in Syria under Apollinaris the Younger, who was the bishop of Laodicea in 361 A.D.
Apollinaris asserted that Jesus did not have a true human mind but was replaced by the Logos of God. Further, it was impossible for Jesus as God, to have both the nature of God and the nature of man dwelling within the body of Jesus at once time. Although this is precisely what the New Testament declares and the Old Testament predicts, this reality is denied.
Not understanding the virgin birth of Jesus which excluded Him from a sin nature, Apollinaris stated that because sin dwells in the spirit of all men that Jesus being both God and man, would also be a sinner.
Of course, Jesus possessed both the nature of God and the nature of man, simultaneously and this was nothing difficult for God to accomplish.
Apollinarianism was rejected by the Second General Council at Constantinople in 381 A.D.
This heresy inevitably seeks to reduces and diminish the true nature of Jesus as both God and man, distorting the atoning work of His death for the sins of the world. These errors always result due to a lack of knowledge in the word of God and a misunderstanding in the text that is being read.
The important doctrine that Jesus is both God and man is known as the Hypostatic Union and is essential to a correct understanding of salvation, according to the Bible
In the beginning was the Word, and the Word was with God, and the Word was God…and the Word became flesh and dwelt among us . ~John 1:1,14
For in Jesus dwells all the fullness of deity in bodily form. ~Colossians 2:9 (RCR)