We live in an age that seems intent on narrowing the gospel to even singular issues. What I find in these discussions is not that the person who argues for a singular issue (as central or the most important element) is wrong but imbalanced. To reduce the gospel to a singular issue runs the serious risk of missing the expansiveness of the gospel as it is presented in the Bible. Not only do we have to examine texts like those in the Psalms or Isaiah, but also those in Jesus (and the Evangelists) and Paul and Peter and James and Hebrews — and not let any of these take total control. Which leads us today to Luke 3:18.
John the Baptist was also a gospel preacher: “3:18 So, with many other exhortations, he proclaimed the good news to the people. 19 But Herod the ruler, who had been rebuked by him because of Herodias, his brother?s wife, and because of all the evil things that Herod had done, 20 added to them all by shutting up John in prison.”
Not only do we know that Jesus was a gospeler and that he got himself imprisoned for gospeling, but we can jump back and see what he preached to see what the gospel was for John the Baptist. I have the text below, but I give the big picture first:
1. His message was shaped by Isaiah’s prophecy of the return to Jerusalem by the Babylonian exiles: his gospel announced some kind of “return.”
2. His message was shot through and through with a sense of God rectifying wrongs, and this rectification was salvation.
3. His message involved the call to repentance and the turn to good works.
4. His message involved the threat of judgment on Israelites who did not repent.
5. His message saw repentance as economic justice.
6. His gospel message pointed to Jesus as the Messiah, who would baptize with more than water. He would baptize with “the Holy Spirit and fire.” (I take this to be a purging empowerment for repentance and moral revolution.)

3 He went into all the region around the Jordan, proclaiming a baptism of repentance for the forgiveness of sins, 4 as it is written in the book of the words of the prophet Isaiah,
?The voice of one crying out in the wilderness:
?Prepare the way of the Lord,
make his paths straight.
5 Every valley shall be filled,
and every mountain and hill shall be made low,
and the crooked shall be made straight,
and the rough ways made smooth;
6 and all flesh shall see the salvation of God.??
Luke 3:7 John said to the crowds that came out to be baptized by him, ?You brood of vipers! Who warned you to flee from the wrath to come? 8 Bear fruits worthy of repentance. Do not begin to say to yourselves, ?We have Abraham as our ancestor?; for I tell you, God is able from these stones to raise up children to Abraham. 9 Even now the ax is lying at the root of the trees; every tree therefore that does not bear good fruit is cut down and thrown into the fire.?
Luke 3:10 And the crowds asked him, ?What then should we do?? 11 In reply he said to them, ?Whoever has two coats must share with anyone who has none; and whoever has food must do likewise.? 12 Even tax collectors came to be baptized, and they asked him, ?Teacher, what should we do?? 13 He said to them, ?Collect no more than the amount prescribed for you.? 14 Soldiers also asked him, ?And we, what should we do?? He said to them, ?Do not extort money from anyone by threats or false accusation, and be satisfied with your wages.?
Luke 3:15 As the people were filled with expectation, and all were questioning in their hearts concerning John, whether he might be the Messiah, 16 John answered all of them by saying, ?I baptize you with water; but one who is more powerful than I is coming; I am not worthy to untie the thong of his sandals. He will baptize you with the Holy Spirit and fire. 17 His winnowing fork is in his hand, to clear his threshing floor and to gather the wheat into his granary; but the chaff he will burn with unquenchable fire.?