This is something I believe to the depths of my soul, and I am going to try to explain this as simply as possible. (which may be hard because I tend to be detail oriented).
The Gospel, is essentially good news. Not good advice, not helpful hints. It is the greatest news anyone could ever hope to receive. But to receive it you may need some background information, so here goes nothing….
In the Beginning God created the heavens and the earth. (Gen. 1:1)
Man (as humanity) sinned (Gen 3). This sin then polluted humanity from that point forward and as such we all have sinned and fallen short of the Glory of God. (Romans 3:23)
Sin is a problem, because it separates us from God. Because God is Holy (or set apart) Just, Merciful, Gracious, Giving, Jealous and Loving, he cannot tolerate sin. You have sinned, I have sinned, we have ALL sinned and fallen short of the Glory of God.
God gave humanity “the law” (see Old Testament), to help reconcile humanity back to God. The Shedding of innocent blood (often Lamb’s) was needed for the cleansing of sin. The law also foreshadowed the coming of Jesus (Matt 5:17)
Because God loved us so much God sent his only Son (Jesus), to be fully God and Fully man to the earth (John 1:1-3). Jesus lived a perfect life, and committed no sin. Jesus freely laid down his life to take away our sin, that however believes in Him will not spend eternity in hell (removed from God/ Jesus) but will be able to spend eternity with God/Jesus. (John 3:16)
That is the bare bones of it. I tried to keep it simple and not go off on a tangent with doctrine or historical evidence or proof (of which there is A LOT, if you look).
I pray for those who have not accepted Jesus as their Savior because I do not want them to parish but to see the beauty of God.