Many cults have latched on to that verse to say that Christ was a created being himself. After all, doesn't "first-born" imply, or even state outright, that Christ was"born"? Hence, he was the first creature made by the Father. The title is used in other portions of the Bible to indicate the first born of a family and rules out earlier children (Genesis 4:4; Exodus 4:22, 23).
The fallacy of this argument that "first-born," when used of Christ meant a creature and not the Creator, is not difficult to see. The argument assumes that the phrase "first-born" always means a starting point. Actually, the title also assumed the idea of "exalted one." Note the Psalmist's use of the term when speaking about David. "I also shall make him [David] My first-born, the highest of the kings of the earth"(Psalm 89:27). David was the youngest of Jesse's sons, not the oldest. He became the first-born of God which meant a title of exaltation.
(ht: Dr. John Williamson)