The three-bar cross is characteristic but not the sole Eastern Christian form; the Greek cross of four equal arms is older and dominates Byzantine architecture and iconography, and the Oriental Orthodox churches, Coptic, Armenian, Ethiopian and Syriac, use crosses of their own design unrelated to the Slavic pattern. The slanted footrest has been given other explanations, a literal footrest shown in perspective, or the crooked made straight, but the two-thieves reading is the one carried in the liturgical hymns sung during Holy Week.
In Russia the cross's exact form became a matter of open conflict during the seventeenth-century schism, when Patriarch Nikon's reforms to bring Russian practice into line with contemporary Greek usage, including changes to the sign of the cross made with the hand and to liturgical texts, were rejected by the communities who became known as Old Believers, who held that the older Russian forms, not the imported Greek ones, were the more faithful. Millions were persecuted or fled after the 1666-1667 councils condemned them, and their descendants remain a living, self-governing tradition today, in Siberia, in the Danube delta as the Lipovans, and in North American settlements from Erie, Pennsylvania to Oregon and the Kenai Peninsula of Alaska, where the older cross forms and the two-finger sign of the cross are still kept exactly as the seventeenth century left them.