Honestly, I’m a poorly catechized Catholic, who is just starting to learn more about my faith.
I’d say something like:
God humbled Himself, became man, and died for us, so that we may have eternal life.
Don't let the catechism lead you away from the Truth go to your Bible. Probably the best explanation of The Gospel is ICor. 15:1-4.
Seek the Truth. We are in a spiritual war and we need warriors.