We do everything we do because Jesus did what he did. We call this the gospel.
What is the gospel?
The word gospel literally means "good news." The gospel is the good news about what Jesus Christ has done to reconcile sinners to a holy God. This good news can be broken down into four sections: God, Man, Christ, and Response.
God is the Creator of all things (Gen. 1:1). He is perfect, pure, holy, worthy of all worship, and will punish sin (1 John 1:5, Rev. 4:11, Rom. 2:5-8). This holy God made us in His image to know him (Gen. 1:26-28).
Even though as human beings we were created in God's image, we have become sinful by nature (Gen. 1:26-28, Ps. 51:5, Rom. 3:23). The first human beings Adam and Eve sinned against God in the Garden of Eden (Gen. 3) and because of that we are all born with a sinful nature, a bent to disobey God. This means that from birth all people are alienated from God, hostile to God, and subject to the wrath of God (Eph. 2:1-3). Because of our sinful nature we cannot possibly bridge the gap between us and God in our own strength and power. We cannot possibly be holy enough to be right with a holy God. Even our righteousness is like filthy rags (Is. 64:6).
Knowing this but still loving us (Rom. 5:8), God sent His son Jesus. Jesus, who is fully God and fully man, lived a sinless life, died on the cross to bear God's wrath in the place of all who believe in him, and rose from the grave in order to give his people eternal life (John 1:1, 1 Tim. 2:5, Heb. 7:26, Rom. 3:21-26, 2 Cor. 5:21, 1 Cor. 15:20). It's only through Christ that we can be reconciled to God - he is our Mediator and our great High Priest (Mark 10:45; John 1:14; Heb. 7:26; Rom. 3:21-26, 5:12-21).
In response to this God calls us to repent of our sins and trust in Christ alone for our forgiveness (Acts 17:30, John 1:12). If we repent of our sins and trust in Christ, we are born again into a new life, and eternal life with God (John 3:16).
Mark 1:15, Acts 20:21, Rom. 10:9-10
That is the best news you're ever going to hear.