What is the Gospel?
"Now I would remind you, brothers, of the gospel I preached to you, which you received, in which you stand, and by which you are being saved, if you hold fast to the word I preached to you—unless you believed in vain. For I delivered to you as of first importance what I also received: that Christ died for our sins in accordance with the Scriptures, that he was buried, that he was raised on the third day in accordance with the Scriptures..." (1 Corinthians 15:1-4)
God created us for his glory.
"Bring my sons from afar and my daughters from the ends of the earth,... whom I created for my glory." (Isaiah 43:6-7). God made us to magnify his greatness - the way telescopes magnify stars. He created us to put his goodness and truth and beauty and wisdom and justice on display. The greatest display of God's glory comes from deep delight in all that he is. This means that God gets the praise and we get the pleasure. God created us so that he is most glorified in us when we are most satisfied in him.
Every human should live for God's glory.
"So whether you eat or drink or whatever you do, do it all for the glory of God." (1 Corinthians 10:31). If God made us for his glory, it is clear that we should live for his glory. Our duty comes from his design. So our first obligation is to show God's value by being satisfied with all that he is for us. This is the essence of loving God (Matthew 22:37) and trusting him (1 John 5:3-4) and being thankful to him (Psalm 100:2-4) It is the root of all true obedience, especially loving others (Colossians 1:4-5).
All of us have failed to glorify God as we should.
"All have sinned and fall short of the glory of God." (Romans 3:23). What does it mean to "fall short of the glory of God?" It means that none of us has trusted and treasured God the way we should. We have not been satisfied with his greatness and walked in his ways. We have sought our satisfaction in other things, and treated them as more valuable than God, which is the essence of idolatry (Romans 1:21-23). Since sin came into the world we have all been deeply resistant to having God as our all-satisfying treasure (Ephesians 2:3). This is an appalling offense to the greatness of God (Jeremiah 2:12-13).
All of us are subject to God's just punishment.
"The wages of sin is death..." (Romans 6:23). We have all belittled the glory of God. How? By preferring other things above him. By our ingratitude, distrust and disobedience. So God is just in shutting us out from the enjoyment of his glory forever. "They will suffer the punishment of eternal destruction and exclusion from the presence of the Lord and from the glory of his might" (2 Thessalonians 1:9)
God sent his only son Jesus to provide eternal life and joy.
"Here is a trustworthy saying that deserves full acceptance: Christ Jesus came into the world to save sinners..." (1 Timothy 1:15). The good news is that Christ died for sinners like us. And he rose physically from the dead to validate the saving power of his death and to open the gates of eternal life and joy (1 Corinthians 15:20). This means God can acquit guilty sinners and still be just (Romans 3:25-26). "For Christ died for sins once for all, the righteous for the unrighteous, to bring us to God" (1 Peter 3:18). Coming home to God is where all deep and lasting satisfaction is found.
The benefits purchased by the death of Christ belong to those who repent and trust him.
"Repent, then, and turn to God, so that your sins may be wiped out" (Acts 3:19). "Believe in the Lord Jesus and you will be saved" (Acts 16:31). "Repent" means to turn from all the deceitful promises of sin. "Faith" means being satisfied with all that God promises to be for us in Jesus. "He who believes in me," Jesus says, "shall never thirst" (John 6:35). We do not earn our salvation. We cannot merit it (Romans 4:4-5). It is by grace through faith (Ephesians 2:8-9). It is a free gift (Romans 3:24). We will have it if we cherish it above all things (Matthew 13:44). When we do that, God's aim in creation is accomplished: He is glorified in us and we are satisfied in him -forever.