I would encourage all of you to continue to engage with this question. There is perhaps no more important thing you can answer. That is because the Gospel is the good news of God. It is something all of us need EVERY day; believer and unbeliever.
Dr. Don Carson in his editorial to the wonderful Themelios Journal gives some great insight into what the gospel is and is not.
It is worth your time to read the whole editorial but at least read this snippet, then take a moment today and preach the Gospel to yourself.
By contrast, the first two greatest commands—to love God with heart and soul and mind and strength, and our neighbor as ourselves—do not constitute the gospel, or any part of it. We may well argue that when the gospel is faithfully declared and rightly received, it will result in human beings more closely aligned to these two commands. But they are not the gospel. Similarly, the gospel is not receiving Christ or believing in him, or being converted, or joining a church; it is not the practice of discipleship. Once again, the gospel faithfully declared and rightly received will result in people receiving Christ, believing in Christ, being converted, and joining a local church; but such steps are not the gospel. The Bible can exhort those who trust the living God to be concerned with issues of social justice (Isa 2; Amos); it can tell new covenant believers to do good to all human beings, especially to those of the household of faith (Gal 6); it exhorts us to remember the poor and to ask, not “Who is my neighbor?” but “Whom am I serving as neighbor?” We may even argue that some such list of moral commitments is a necessary consequence of the gospel. But it is not the gospel. We may preach through the list, reminding people that the Bible is concerned to tell us not only what to believe but how to live. But we may not preach through that list and claim it encapsulates the gospel. The gospel is what God has done, supremely in Christ, and especially focused on his cross and resurrection.