Mark 1:15: “The kingdom of God is at hand; repent and believe in the gospel.”
The word "gospel" (euangelion) means good news. The gospel is the good news of the person and work of Jesus Christ - His perfect life, sacrificial death, and victorious resurrection to reconcile sinful man to holy God by grace through faith for the glory of God.
There is one eternal, infinite, holy God who is perfect in all His ways (Isaiah 44:6; Deuteronomy 32:3-4). He is the Creator and Sovereign Ruler of the universe (Revelation 4:11; Psalm 103:19).
God formed man and woman in His own image to rule in His very good creation (Genesis 1:31). But they disobeyed God’s Word and caused separation from God and suffering in the world (Habakkuk 1:13; Isaiah 59:2; Romans 5:12; 6:23). Since then, all people have fallen short of God’s holy standard and deserve condemnation (1 Peter 1:16; Romans 3:23; Isaiah 53:6; Ecclesiastes 7:20). There is no one righteous before God or anyone who is able to please Him on their own (Romans 3:10-12; 8:7-8; Proverbs 20:9). Even one sin brings guilt under the law (James 2:10). But God provided a way for man to be reconciled to this God whose justice demands punishment for sin. It is not by works of righteousness or human virtue (Titus 3:5-7; Isaiah 64:4; Ephesians 2:8-9). By nature, all of us are helpless enemies of God who are enslaved to various sins, dead in sin, and without excuse (Romans 1:18-20; 5:6; Isaiah 6:5; Ephesians 2:4; Titus 3:3, John 8:34; Romans 5:10; 8:7; James 4:4). The infinite debt owed for sin requires infinite payment, so man is headed to eternal conscious punishment unless God provides rescue, as He did in Christ.
God, being rich in mercy, according to His predetermined plan, because of His great love, gave His Son, the promised Messiah, to bring to life those who were dead in transgressions (Ephesians 2:5; Isaiah 7:14). God the Son entered human history as the man Jesus Christ, being fully God and fully man (Hebrews 1:3; John 1:1-2; John 8:58, 10:20; Colossians 1:15). He suffered in the flesh and was tempted in all things, yet He fully kept the law and was without sin (Matthew 5:17; Hebrews 4:15). He lived a perfect life and yet gave Himself to die for the sins of all who trust Him. God the Father treated Jesus as guilty for the sins of all His people and Jesus exclaimed “It is finished!” as He died, because the penalty for sin had been paid (Isaiah 53:6; John 19:30). Jesus was punished so that all who repent and believe in Him can receive His righteous life (2 Corinthians 5:21). On the third day, Jesus rose triumphantly from the grave as He said He would do, defeating sin, death, and the devil (1 Corinthians 15:55-57; Matthew 20:19; Hebrews 2:14). He secured justification and new life for His people and ascended to the right hand of the Father (Romans 4:25; 6:4; Hebrews 8:1; Acts 5:31). Salvation is found in Jesus Christ alone. He is just, and He is also Justifier (Romans 3:24-26). He has done what man could not do. He is the way, the truth, and the life—no one comes to the Father except through Him (John 14:6). Now for those in Christ Jesus, there is no condemnation but instead, peace with God (Romans 8:1; 5:1). Apart from Christ, there is only condemnation and wrath awaiting every sinner (John 3:36). There is no escape for those who neglect this message (Hebrews 2:3)—they will pay the penalty of eternal destruction, forever separated from God (2 Thessalonians 1:9).
This Gospel is freely offered for all to call upon His name and be saved (Romans 10:13). Scripture says to turn from sin (repent) and entrust oneself to Jesus (Acts 2:36-40; 16:31; 17:30-31). For those who confess their sins, God is faithful and righteous to forgive them of their sins and cleanse them from all unrighteousness (1 John 1:9). The death and resurrection of Jesus is more powerful than any sin ever committed and sufficient to wash and pardon completely (Romans 5:20). Redemption and reconciliation are promised to the one who has faith in Christ and His atoning work. By grace, through faith, the sinner is regenerated, converted, justified, adopted, sanctified, kept, and glorified all for the glory of God (Ezekiel 11:19-20; Acts 3:19; Romans 3:21-26; Galatians 4:4-5; Hebrews 7:25; 1 Peter 1:5; Romans 8:29-30). The Father so loved the world that He demonstrated that love in giving His only Son for this purpose—to the praise of His glorious grace (Romans 5:8; John 3:16; Ephesians 1:6). He says to the one who comes to Him that He will never cast him out (John 6:37). There is salvation and life in no one else, for there is one Mediator between God and man—the man Christ Jesus and He is mighty to save (Acts 4:12; 1 John 5:12; 1 Timothy 2:5-6).
The forgiven and reconciled man has a new Master and is no longer enslaved to sin--but to God (Romans 6). He is born of the Spirit as a child of God (John 3:8; Romans 8:9-11; Galatians 3:26), made a new creation, knows God in eternal life and fellowship (2 Corinthians 5;17; John 17:3; 1 John 1:3), granted all things for life and godliness to walk in good works (2 Peter 1:3; Ephesians 2:10) and has a secure, lasting inheritance in the eternal, unshakeable kingdom where he will be presented faultless before the throne of God (1 Peter 1:3-4; Hebrews 12:28; Jude 24).
The fruit of the Holy Spirit in the child of God is obedience and love for God and His Word (1 John 2:3; 1 Thessalonians 2:13). Believers can have confidence in the day of judgment because Christ suffered to bring sinners to God forever for His name’s sake (1 Peter 3:18; Jude 25; 1 John 2:12, 28; Philippians 1:6).
This is good news from the faithful and trustworthy God. From Him and through Him and to Him are all things. To Him be the glory forever. Amen (Romans 11:36).