Contrary to the beliefs of many people in the first century and even in our era, the primary purpose of Jesus in coming to earth to minister was not to heal the sick or perform other signs and wonders. As important as these tasks were, they were secondary to His mission of preaching the truth. That is what we read in today's passage. When Simon and the other disciples came to Jesus to encourage Him in His ministry of healing, pointing out the fact that many people were looking for Him, Jesus did not decide to stay in Capernaum and continue healing. He instead said that it was time for Him to preach in other Galilean towns, for His reason for coming was to preach (Mark 1:36–38).
Specifically, Jesus came to preach the very thing Mark described in 1:14–15, namely, the gospel of God. The signs and wonders our Lord performed testified to the truth of His message, but they were not ends in themselves. In fact, a miracle does no ultimate good for the people who receive it if they reject the gospel. Preaching the truth about the kingdom of God and how one may receive it by trusting only in Christ formed the bulk of His message, and this message of faith and repentance surpassed all of Jesus' miracles in terms of importance. Note, however, that this message cannot be separated from His work of atonement. Jesus "came to seek and to save the lost" (Luke 19:1–10), and this salvation comes through the pouring out of His blood "for many for the forgiveness of sins" (Matt. 26:26–29). In coming to preach the gospel of God, Jesus came to preach Himself. He came as both the messenger and the message—without the atonement, there is no good news to proclaim. And when this good news is proclaimed accurately, it pushes back the kingdom of darkness, as we see in the mention of exorcisms alongside Jesus' preaching ministry in Mark 1:39.
Christ did not go out on this preaching ministry in greater Galilee until He first spent time praying in "a desolate place" (v. 35). This setting was similar to the wilderness in which Jesus was tempted by Satan but stood firm against the devil's attacks and received sustenance from His Father (Matt. 4:1–11). Jesus' going out to pray represented His seeking the face of His Father to sustain Him in His resolve to complete the mission God gave Him, to be prepared inwardly and spiritually so that He could exercise His outward preaching ministry.
If Jesus, who is the Son of God incarnate, found it so necessary to pray, shouldn't we also pray? Fellowship with the Lord in prayer is an absolute necessity if we will be sustained in life and ministry over the long haul. This is true whether we minister as pastors, in secular workplaces, or in our homes.