Matthew 4 begins with the temptation of Jesus in the desert. Satan used truths and scripture to tempt Jesus in to doing the wrong thing. One of the answers Jesus gave to Satan’s temptations was Matthew 4:4
. . .Man does not live on bread alone, but on every word that comes from the mouth of God.
Jesus pointed out that we need to follow every word of God, and not just pick and choose what we want.
Next, the scripture explains another messianic prophecy that Jesus fulfilled by moving to Capernaum (Matthew 4:12-16). In verse 17 Jesus starts his public ministry:
From that time on Jesus began to preach, “Repent, for the kingdom of heaven is near.”
Here we see that the message of Jesus from the point he started his ministry until his ascension to heaven was for people to repent from their sin. And if we continue to read every word from the mouth of God, we find out that the only way to truly repent from sin is to be renewed or reborn through making Jesus Lord of our lives and receiving the Holy Spirit.
The chapter continues with Jesus Gathering some disciples. Jesus tells them in verse 19:
Come, follow me and I will make you fishers of men.
And in verse 23:
Jesus went throughout Galilee, teaching in their synagogues, preaching the good news of the kingdom, and healing every disease and sickness among the people.
As you can see, verses 19 and 23 emphasis spreading the Gospel.