Ordo domus Sanctæ Mariæ Theutonicorum Ierosolimitanorum (Order of the German House of St. Mary in Jerusalem) is the name of some ancient Teutonic German Knights. They began at the end of the 12th century as a Roman Catholic religious order and became a crusading militia in the Middle Ages bearing a black cross on their white tunics. In the 19th century their commanders wore a black Maltese Cross around their necks, which was called the Marian Cross.
A Jewelled Cross used in Ave Maria devotions is sometimes referred to as a Marian Cross or Mater Cross, as is a crucifix which includes an image of the Virgin Mary, although this style may also be called a Unity Cross, symbolising the two-in-oneness of Jesus and Mary.
Any style of cross, with or without a corpus, and adorned with a letter 'M', of any proportion, might be referred to as a Marian Cross. The 'M' may be superimposed on the cross beam, or as in our example above, in the lower right quadrant. (See also the Calatrava Cross.)
Arms of Pope John Paul II
The 'M' refers to Mary's station at the foot of the cross and symbolizes her vocation as Mater Dolorosa (Mother of Sorrows). The Roman Catholic Pope John Paul II, known as a very Marian pope, had a personal coat-of-arms with an 'M' beneath the right arm of the cross.
Roman Catholics often refer to Mary as "The Mother of God", which takes a bit of effort to understand properly.
A non-Catholic view
Protestants point out that God existed long before Mary was alive, and actually doesn't have a mother, but they gladly acknowledge that Mary was the channel through which Jesus became human.
Very little is written about Mary in the Bible. There is no doubt she was a remarkable woman, chosen by God to introduce Jesus to the world, but there is nothing in the Bible that instructs Christians to worship or pray to Mary. As 1 Timothy 2:5 says: "For there is one God, and one mediator between God and men, the man Christ Jesus". Worshipping Mary is idolatry.
A Catholic view
Let's put the record straight...
True Catholics do NOT worship Mary, or statues of Mary. Catholics are as fully aware as Protestants that idolatry is absolutely against God's law and Biblical teaching. Yet the Bible does cite instances of statues being used as a spiritual aid (Num. 21:8-9, for example). And Mary, the Mother of Jesus, and therefore the Mother of God, is elevated to a similarly revered position as the Cross, for the focus of worshipping God.
Mary is not worshipped, but she is recognised as being the greatest of all of God's creations, great enough to be the Blessed Mother of Jesus. And for this she is honoured. She is honoured not for who she was, but for whom God made her to be.
So there is very little difference between the two faiths. Mary is honoured, rightly so with awe, for her role as the Blessed Mother of Jesus.
A much less ornately decorated Marian Cross is shown on the next page