The Ox is The Gospel of St. Luke's Symbol

      "St. Luke's is the Gospel for the Greeks, the Gospel of the future, the Gospel of progressive Christianity, of the universality and gratuitousness of the Gospel, the historic Gospel, the Gospel of Jesus as the Good Physician and Savior of Mankind." 

       His emblem is the ox: expressing power and sacrifice, Christ's priestly and mediatorial office.

Scriptural Resources for The Gospel of St. Luke's Symbol - An Ox:

• "But Jesus was saying, "Father, forgive them; for they do not know what they are doing." And they cast lots, dividing up His garments among themselves." Luke 23:47 (NIV)
• "But Jesus was saying, "Father, forgive them; for they do not know what they are doing." And they cast lots, dividing up His garments among themselves." Luke 6:27 (NLT)
• "And He withdrew from them about a stone's throw, and He knelt down and began to pray, saying, "Father, if You are willing, remove this cup from Me; yet not My will, but Yours be done." Luke 22: 41-42 (NASB) 
• "But Jesus was saying, "Father, forgive them; for they do not know what they are doing." And they cast lots, dividing up His garments among themselves." Luke 23:34 (NASB)

The above Gospel of St. Luke is by Rudolf Koch.