Scholars generally agree that Mark was the first written Gospel. As a result, critics often claim that the doctrine of the deity of Christ does not appear clearly in Mark but emerges later in the Gospel of John.
While there are certainly explicit claims to deity in John, such as when Jesus says, “Truly, truly, I say to you, before Abraham was, I am” (8:58), this critical challenge overlooks distinct proclamations of the deity of Christ throughout the Gospel of Mark.
Here is my contention: From the first chapter until the end, the Gospel of Mark proclaims that Jesus understood himself to be God. Consider six brief examples:
1. MARK 1:2-3: Mark begins his Gospel by citing a passage from Isaiah 40:3, which discusses how a messenger would come, like a voice of one crying in the wilderness, and “Prepare the way of the Lord.” In the original context, the messenger would prepare the way “for our God.” But Mark substitutes Jesus as the Lord who is coming and John the Baptist as the messenger. In other words, John the Baptist is preparing the way for God himself to come in the person of Jesus Christ.
2. MARK 2:1-10: In this passage, Jesus heals a paralytic brought to him by four friends. When Jesus first sees him, he says, “Son, your sins are forgiven.” The scribes instantly object, “He is blaspheming! Who can forgive sins but God alone?” They believed the man was paralyzed because he had sinned against God, and yet Jesus had the audacity to claim that he could personally forgive these sins. The scribes are right that only God can forgive sins (Exodus 34:6-7; Psalm 103:3). Not even the Messiah could forgive sins. In this instance, however, Jesus bypasses the normal route of how forgiveness was received (Leviticus 4:20) and claims to speak with God’s authority. Why? Because he understood himself to be God.
3. MARK 2:27-28: In this passage, Jesus and his disciples pluck heads of grain on the Sabbath, but the Pharisees object that such behavior violates the law. Jesus responds with an example of how David did the very same thing in the time of Abiathar the high priest. And then after explaining how the Sabbath was made for man, rather than vice versa, Jesus makes an even more provocative claim: “So the Son of Man is lord even of the Sabbath.” In other words, Jesus claims to have authority over the Sabbath, which was instituted by God at creation (Gen 2:3). Once again, Jesus claims to have the authority of God within himself. Jesus furthers his claim to divine authority over the Sabbath by healing a man in the synagogue (Mark 3:1-6).
4. MARK 3:13-19: In this passage, Jesus calls his twelve apostles to be with him, preach, and have authority to case out demons. The number twelve is significant, and recalls the twelve tribes of Israel (Genesis 35:22-26). The twelve will continue the ministry of Jesus, but also sit in judgment over Israel (Matthew 19:28). Since God originally established Israel and the twelve tribes, by what authority can Jesus reform the twelve? The answer is, once again, that Jesus speaks with the authority of God himself.
5. MARK 6:45-52: Jesus walks on the water in this passage and his apostles were terrified to see him. He responds, “Take heart, it is I. Do not be afraid.” The Greek for “It is I” (egō eimi) is identical to how God revealed himself to Moses as “I am” (Exod. 4:3; 6:6; Isaiah 43:10-11). By walking on water, Jesus was also walking in God’s stead, since only God can walk on water (Job 9:8; Psalm 77:19; Is. 43:16). Thus, in both word and deed, this passage presents Jesus with a divine understanding.
6. MARK 14:60-62: In the climax of the Gospel of Mark, Jesus stands falsely accused before the chief priests, elders, and scribes. The high priest asks Jesus directly if he is the Messiah. And Jesus responds, “I am, and you will see the Son of Man seated at the right hand of Power, and coming with the clouds of heaven.” The high priest tears his clothes in response and claims that Jesus has committed blasphemy. Why? Because Jesus quoted Daniel 7:13 in reference to himself, a passage in which the “Son of Man” is a divine figure who will rule God’s kingdom for eternity.
There are many other examples throughout the Gospel of Mark that indicate Jesus saw himself as divine. But these should be sufficient to show that the deity of Christ is not a late invention creeping into the later Gospels but appears in the (probably) earliest Gospel, Mark.
 Conservative scholars generally date the Gospel of Mark in the late 50s to late 60s and liberal scholars in the 70s, after the destruction of the Temple.