'Preaching' in the Bible

John the Baptist appeared in the wilderness preaching a baptism of repentance for the forgiveness of sins [that is, requiring a change of one’s old way of thinking, turning away from sin and seeking God and His righteousness].

Now after John [the Baptist] was arrested and taken into custody, Jesus went to Galilee, preaching the good news of [the kingdom of] God,

So He went throughout Galilee, preaching [the gospel] in their synagogues and casting out demons.