For those not familiar with the story of St. Nicholas and Arius at the Council of Nicea, my opening remark might require a little explanation.
Rather than go into a history of St. Nicholas, Pastor and Bishop of Myra, I'd like to focus more on Arius and Arianism. For background on St. Nicholas, please read some of the plethora of posts on the topic from places such as Ask the Pastor (Pr. Snyder), Lest Every Man Be Blind (Pr. Koch) and Aardvark Alley. Today (6 December) is, by the way, the Feast Day for St. Nicholas.
Before we get to the fun, here's a brief synopsis of Arianism.
Arianism is the 4th century teaching of Arius which denied the divinity of Jesus and the essence of the Trinity (antitrinitarian). Arius taught that the Father created the Son as His first creation. The Son then created the Holy Ghost, and the universe after that (not the Father or the Trinity, only the Son). Christ was considered to be adopted by the Father since He was merely a creation of the Father’s, but because He had great position and authority, He was to be looked upon by humans as a God and worshiped accordingly. At the First Council of Nicaea in 325, Arius was declared a heretic (the Nicene Creed was written specifically to counter his false teachings), exonerated at the First Synod of Tyre in 335 after recanting his heresy, and condemned again posthumously in 381 at the First Council of Constantinople (where the Nicene Creed was slightly modified to combat Macedonianism). Arianism had one of the largest followings of any heresy, and it was feared that they might grow so large as to take over the church. Their main teaching, that the Son of God did not always exist, and is distinct from and “less” than the Father because He was created by the Father, existed as a human (but heretical) way to help explain the Hypostatic Union of Christ’s two natures and attempt to humanize the Trinity.
As the story goes, at the Council of Nicea there were many heated discussions between Arius and his followers, and the Orthodox Bishops in attendance. During one of these lively exchanges, St. Nicholas is said to have slapped Arius for his heresy. St. Nicholas was then banned from the council until he apologized. Puts a whole new light on Santa, doesn't it?
Why would a Bishop get so worked up that he would actually resort to hitting someone? The teaching of Arius was so pervasive at the time that many were worried it would take over the Church. As mentioned before, it is an understandable human way to try and describe the unexplainable but that does not make it any less heretical
Ultimately, it comes down to how one views the relationship between God the Father and God the Son: homousian ("of the same substance", the Orthodox teaching) or heterousian ("differing in substance", the heretical, or Arian, teaching). Now might be a good time to review my post on the Trinity for more on how the Trinity works.
While this story may be just a legend (although records of Nicholas being 'suspended' and 'reinstated' seems to verify it to a large degree), the lesson from it is very important: we should take heresy very seriously, and so what we can to stamp... or slap... it out.
And, since we're on this topic, while we don't see much pure Arianism today, we do see some Semi-Arianism (or Macedonianism) floating about from time to time.
Anti-trinitarian heresies are a particular pet peeve of mine because they deny the most basic of our Christian beliefs, or attempt to make the idea of our unity in Trinity and Trinity in unity more palatable to "logic". Doubt there, and why even bother being a Christian otherwise? Anti-trinitarian heresies are pervasive today in various incarnations, often more subtle or in different form from Arianism, but they're still alive and kicking. Maybe we need to take a page out of good ol' St. Nick's book and start slapping a few heretics of our own... at least mentally.