What is the Gospel?

Greek: euangelion, “good news”

Isaiah 40:9
9 Get yourself up on a high mountain, O Zion, bearer of good news, lift up your voice mightily, O Jerusalem, bearer of good news; lift it up, do not fear. Say to the cities of Judah, “Here is your God!”
10 Behold, the Lord Yehovah will come with might, with His arm ruling for Him. Behold, His reward is with Him and His recompense before Him.
11 Like a shepherd He will tend His flock, in His arm He will gather the lambs and carry them in His bosom; He will gently lead the nursing ewes.

Isaiah 52:6-8
6 Therefore My people shall know My name; therefore in that day I am the one who is speaking, “Here I am.”
7 How lovely on the mountains are the feet of him who brings good news, who announces peace and brings good news of happiness, who announces salvation, and says to Zion, “Your God reigns!”
8 Listen! Your watchmen lift up their voices, they shout joyfully together; for they will see with their own eyes when Yehovah restores Zion.

Isaiah 52:20-22 (cf. Romans 10:12-17)
20 Look upon Zion, the city of our appointed feasts; your eyes will see Jerusalem, an undisturbed habitation, a tent which will not be folded; its stakes will never be pulled up, nor any of its cords be torn apart.
21 But there the majestic One, Yehovah, will be for us a place of rivers and wide canals on which no boat with oars will go, and on which no mighty ship will pass.
22 For Yehovah is our judge, Yehovah is our lawgiver, Yehovah is our king; He will save us.

Matthew 24:11-14
11 Many false prophets will arise and will mislead many.
12 Because lawlessness is increased, most people’s love will grow cold.
13 But the one who endures to the end, he will be saved.
14 This gospel of the kingdom shall be preached in the whole world as a testimony to all the nations, and then the end will come.

Romans 10:12-17 (cf. Isaiah 52:6-8)
12 For there is no distinction between Jew and Greek; for the same Lord is Lord of all, abounding in riches for all who call on Him;
13 for “Whoever will call on the name of Yehovah will be saved.”
14 How then will they call on Him in whom they have not believed? How will they believe in Him whom they have not heard? And how will they hear without a preacher?
15 How will they preach unless they are sent? Just as it is written, “How beautiful are the feet of those who bring good news of good things!”
16 However, they did not all heed the good news; for Isaiah says, “Lord, who has believed our report?”
17 So faith comes from hearing, and hearing by the word of Messiah.

2 Thessalonians 2:3-4, 8-10
3 Let no one in any way deceive you, for it will not come unless the apostasy comes first, and the man of lawlessness is revealed, the son of destruction,
4 who opposes and exalts himself above every so-called god or object of worship, so that he takes his seat in the temple of God, displaying himself as being God.
8 Then that lawless one will be revealed whom the Lord will slay with the breath of His mouth and bring to an end by the appearance of His coming;
9 that is, the one whose coming is in accord with the activity of Satan, with all power and signs and false wonders,
10 and with all the deception of wickedness for those who perish, because they did not receive the love of the truth so as to be saved.

James 4:12
There is only one Lawgiver and Judge, the One who is able to save and to destroy.