The word "Gospel" means "Glad news" or "Good Tidings". (See the greek definition from the Blue Letter Bible)
The verses below show the direct connection between the Gospel (or Good News) which Jesus taught, and the coming kingdom to which the good news referred. This kingdom is not in the heavens, but on the earth.
The reason why this kingdom is important, is becuase the uncontious dead will be resurrected back to life, judged at the great judgement seat of Jesus Christ, and if found worthy will be given eternal life.
General verses on the Gospel:
Mark 6:8 And commanded them that they should take nothing for their journey, save a staff only; no scrip, no bread, no money in their purse:
9 But be shod with sandals; and not put on two coats.
10 And he said unto them, In what place soever ye enter into an house, there abide till ye depart from that place.
11 And whosoever shall not receive you, nor hear you, when ye depart thence, shake off the dust under your feet for a testimony against them. Verily I say unto you, It shall be more tolerable for Sodom and Gomorrha in the day of judgment, than for that city.
12 And they went out, and preached that men should repent.
13 And they cast out many devils, and anointed with oil many that were sick, and healed them.
Luke 4:43 And he said unto them, I must preach the kingdom of God to other cities also: for therefore am I sent.
Luke 8:1 And it came to pass afterward, that he went throughout every city and village, preaching and shewing the glad tidings of the kingdom of God: and the twelve were with him,
Acts 8:12 But when they believed Philip preaching the things concerning the kingdom of God, and the name of Jesus Christ, they were baptized, both men and women.
Acts 26:23 That Christ should suffer, and that he should be the first that should rise from the dead, and should shew light unto the people, and to the Gentiles.
1 Corinthians 1:17 For Christ sent me not to baptize, but to preach the gospel: not with wisdom of words, lest the cross of Christ should be made of none effect.
18 For the preaching of the cross is to them that perish foolishness; but unto us which are saved it is the power of God.
19 For it is written, I will destroy the wisdom of the wise, and will bring to nothing the understanding of the prudent.
20 Where is the wise? where is the scribe? where is the disputer of this world? hath not God made foolish the wisdom of this world?
21 For after that in the wisdom of God the world by wisdom knew not God, it pleased God by the foolishness of preaching to save them that believe.
22 For the Jews require a sign, and the Greeks seek after wisdom:
23 But we preach Christ crucified, unto the Jews a stumblingblock, and unto the Greeks foolishness;
24 But unto them which are called, both Jews and Greeks, Christ the power of God, and the wisdom of God.
25 Because the foolishness of God is wiser than men; and the weakness of God is stronger than men.
26 For ye see your calling, brethren, how that not many wise men after the flesh, not many mighty, not many noble, are called:
27 But God hath chosen the foolish things of the world to confound the wise; and God hath chosen the weak things of the world to confound the things which are mighty;
28 And base things of the world, and things which are despised, hath God chosen, yea, and things which are not, to bring to nought things that are:
29 That no flesh should glory in his presence.
30 But of him are ye in Christ Jesus, who of God is made unto us wisdom, and righteousness, and sanctification, and redemption:
31 That, according as it is written, He that glorieth, let him glory in the Lord.
1 Corinthians 15:1 Moreover, brethren, I declare unto you the gospel which I preached unto you, which also ye have received, and wherein ye stand;
2 By which also ye are saved, if ye keep in memory what I preached unto you, unless ye have believed in vain.
2 Corinthians 11:1 Would to God ye could bear with me a little in my folly: and indeed bear with me.
2 For I am jealous over you with godly jealousy: for I have espoused you to one husband, that I may present you as a chaste virgin to Christ.
3 But I fear, lest by any means, as the serpent beguiled Eve through his subtilty, so your minds should be corrupted from the simplicity that is in Christ.
4 For if he that cometh preacheth another Jesus, whom we have not preached, or if ye receive another spirit, which ye have not received, or another gospel, which ye have not accepted, ye might well bear with him.
Galatians 1:8 But though we, or an angel from heaven, preach any other gospel unto you than that which we have preached unto you, let him be accursed.
Galatians 3:6 Even as Abraham believed God, and it was accounted to him for righteousness.
7 Know ye therefore that they which are of faith, the same are the children of Abraham.
8 And the scripture, foreseeing that God would justify the heathen through faith, preached before the gospel unto Abraham, saying, In thee shall all nations be blessed.
9 So then they which be of faith are blessed with faithful Abraham.
Ephesians 1:9 Having made known unto us the mystery of his will, according to his good pleasure which he hath purposed in himself:
10 That in the dispensation of the fulness of times he might gather together in one all things in Christ, both which are in heaven, and which are on earth; even in him:
Ephesians 1:13 In whom ye also trusted, after that ye heard the word of truth, the gospel of your salvation: in whom also after that ye believed, ye were sealed with that holy Spirit of promise,