A Celtic cross is often defined as any cross “which has a circle enclosing the cross beams” The Celtic cross may also be called an Irish Cross, a wheel cross, or a cross of Iona. There are several legends about the origin and thus symbolism of the Celtic Cross.
1. The Celtic cross began as a large, stone, Latin cross. Crosses in this style were sometimes wider at the ends than in the center, so gravity eventually took its toll, breaking one or both of the arms. Scultors discovered that it they could repair these crosses by reconnecting the arms to a ring, thus creating the familiar symbol of the Celtic Cross. If this is true, then the symbolism is fundamentally the same as the symbolism of the Latin cross.
2. St. Patrick is credited for bringing Christianity to Ireland around the year 440. In the process, he found people worshiping a deity with a circle as its symbol. St. Patrick explained to them that was not a god, but that the God who created the sun used a different symbol. He then etched a Latin cross over the circle, and told them the story of the crucifixion. The result was a Celtic Cross. This legend focuses the symbolism of the Celtic Cross on Christ as king.
3. The third possibility is that the Celtic Cross actually developed as a form of the Chi Rho, and was not the result of a moment of inspiration, but of a slow process of artistic evolution. Thus the Celtic cross was born. In this case, the symbolism could focus more specifically on Jesus as Messiah.
Celtic Crosses have become very popular, even in secular art. They are particularly present in Reformed churches, and often serve as a wall crosses or chancel crosses. If you keep your eyes open, you'll find Celtic Crosses in many different places.
The Irish high crosses are also becoming increasingly popular in art, many of which rely on this basic shape. The Monasterboice cross, show on the left is an example of one such cross.
Tell the legend of St. Patrick (above), and then read Psalm 148. What role does the sun play in the passage? Next, consider the possible evolution of the Celtic cross from the Chi Rho, and Philipians 2.1-11. What does it mean for Jesus to be Messiah or Lord in this passage?
Chances are, if you've ever had or used art in your worship space, you've had a Celtic cross at some point. Because it is so common, you likely have had it on a slide, banner, bulletin cover or even a sculpture or wall cross. Because it has become such a common and beautiful decoration, people can become almost numb to its presence. With this in mind, preaching with such a symbol can be challenging. It may be helpful to share one of the legends mentioned above, and to highlight themes of evangelism or atonement to "reclaim" the efficacy of this symbol.
Outside of major ecumenical seasons, it may be fun to use this around St. Patrick's day, as it has become such a widely celebrated holiday in secular culture. It could be jarring, and thus perhaps effective, to make use of this symbol during Holy week, thus juxtaposing the secular, artistic use with the crucifixion.