Following John was Jesus, and he too was a gospeler, one who preached the gospel. Today I want to begin with some general summary passages that set up Jesus as a gospel preacher.

Mark 1:1: The beginning of the good news of Jesus Christ, the Son of God.

Matt. 4:23 Jesus went throughout Galilee, teaching in their synagogues and proclaiming the good news of the kingdom and curing every disease and every sickness among the people. 24 So his fame spread throughout all Syria, and they brought to him all the sick, those who were afflicted with various diseases and pains, demoniacs, epileptics, and paralytics, and he cured them. 25 And great crowds followed him from Galilee, the Decapolis, Jerusalem, Judea, and from beyond the Jordan.
Matt. 9:35 Then Jesus went about all the cities and villages, teaching in their synagogues, and proclaiming the good news of the kingdom, and curing every disease and every sickness.

Mark begins his Gospel with the word gospel; in fact, it is entirely possible that Mark’s Gospel was called a “gospel” because of Mark 1:1. The whole of his book is the narration of the gospel in Jesus Christ, and a good way of summing that up was done by the one who followed Mark: Matthew.
Matthew frames the Sermon on the Mount and the miracle/discipleship passages of Matthew 8–9 with 4:23-25 and 9:35. These two passages are literary markers for us to see that Jesus’ teaching on righteousness and his acts of power and summonings to discipleship are his gospel preaching.
Furthermore, we learn that Jesus’ gospel is a “kingdom gospel.” Kingdom must be defined, and that is no easy task, but whatever you decide there is inherent to what gospeling was all about for Jesus. I take “kingdom” to refer to the society in which the redemptive power of God becomes manifest, in which and through which Gods’ will is done on earth as it is done in heaven, and which is now only partially manifest. Its fullness awaits the Eschaton. That kingdom society is the society that sits at the feet of Jesus, that trusts in/believes in, that loves, and that follows Jesus.
Jesus’ gospel is the announcement that the long-awaited redemptive act of God — seen in Psalms and Isaiah and expected for all those centuries — has now arrived in him and in those who are connected to him.
Let me then put it this way: Jesus is gospel, everything about Jesus is gospel, and gospel isn’t gospel until it is all about Jesus.