Ebionism is an an odd mixture of Christianity and Judaism which was one of the earliest of the Christological heresies that taught that Jesus was NOT divine but was just a 'good' man.
The Ebionites also "accepted only the “Gospel of the Hebrews,” adhered to the Mosaic law, and condemned the Apostle St. Paul as an apostate from the Law. . . .Concerning the birth of Christ they were divided. Some admitted His supernatural birth of a virgin; others held that Christ was only man and the son of Joseph and Mary." (Thein, J., 1900. Ecclesiastical Dictionary)
Ebionism is alive and well in modern times. Sometimes it is taught unintentionally and sometimes it is taught with malicious intent. It can be heard in catechism classes, in seminaries, and even from the pulpit sometimes :( Be firm in knowing that Jesus Christ IS the DIVINE 2nd person of the Blessed Trinity. Any teaching to the contrary is heresy!
Two of my favorite Bible verses to combat Ebionism are:
John 1:1,14 - "In the beginning was the Word: and the Word was with God: and the Word was God. . .And the Word was made flesh and dwelt among us"
Colossians 2:9 - "For in him the whole fulness of deity dwells bodily"
image from the 'Public domain' via wikimedia commons. Sermon on the Mount
Also see other 'Don't be a Heretic' posts here: Gallicanism / Ebionism