What's the gospel?
3. Our sins can be forgiven through faith in Jesus Christ, apart from works of the Law. "And we proclaim to you the good news," Paul says in the synagogue at Pisidian Antioch, " . . . that through [Jesus] forgiveness of sins is proclaimed to you, and by this one everyone who believes is justified from everything from which the law of Moses could not justify you" (Acts 13:32, 38-39; see also Gal. 2:14-16).
The good news is that God no longer must count people's sins against them. He can call them innocent (justify them) even if they have done guilty things. They don't earn an innocent verdict by doing enough good things written in God's Law to compensate for the bad things they've done, because no one can ever do enough. God declares people innocent by nothing other than his free grace (see Acts 20:24). The announcement of this grace is powerful enough to save people (Rom. 1:16) and enable them to be born anew (1 Pet. 1:23, 25) by being sanctified (set apart for God) by the Holy Spirit (2 Thess. 2:13-14).
But this forgiveness, salvation, rebirth, and sanctification only comes to people who repent of (turn away from, reject) their sin (Mark 1:15; see also Luke 1:16-19) and who begin to obey God as a result of their new faith (Rom. 1:1, 5). But the most important condition, which comes up again and again in the Scriptures I've referenced here, is faith—wholehearted trust/belief in the person and work of Christ as the only way one can be saved.
Our sins can be forgiven through faith in Jesus Christ. That's good news.