Even if persons with developmental disability lack the potential to ever reason abstractly, their experience of the Mysteries (the Sacraments) can be just as rich as those who can reach that stage. For the Mysteries have Divine depth, and always beckon one forward to greater participation and fuller comprehension of their import. For the experience ultimately transcends conceptualization.
pictured on the left: an engaged couple. Marriage is one of the Mysteries of the Orthodox Church.
Fr. John Breck, in “Down Syndrome at Pascha,” in his book God With Us: Critical Issues in Christian Life and Faith, describes Marie, a woman who had Down Syndrome, at the Holy Friday service: (pp. 66-67)
“She was entirely dressed in black. Her face was streaked with tears, her head was bowed, and her arms hung down at her sides. As she approached the shroud, she slowly made the sign of the cross three times, prostrated herself before it, and for a moment kept her head to the floor. Then she rose, kissed the face and then the feet of Christ, and finally venerated the Bible and the Cross. “
Here’s a word from the publisher on the book as well as the site through which one may order it: http://www.svspress.com/product_info.php?products_id=79
Of course, one must be baptized and/or chrismated into the Orthodox Church to participate in the Church’s mysteries. Here is an article that addresses our beliefs in this regard: http://www.antiochian.org/node/16917 For more on the Orthodox Church, see also http://www.antiochian.org/node/16958