I think you could start out with the explanation of the creation of man, and God’s plan for salvation. And how that plan was derailed by Adam’s sin, and how God, out of his Divine Love and Mercy planned on redeeming man by sending His only Begotten Son, how he would tell us about God’s love, and how he would suffer and die for us, and on the Third day he would rise from the Dead, and after a while he would go back to the Father, but would send to us a Paraclete, and Comforter, founding his Church, and being with Her until the end of time, and the gates of Hell would not prevail against her.
And in and through His Church, we would find salvation, by the means of grace, the Sacraments, Baptism, Confirmation, Penance, the Eucharist, Extreme Unction, Holy Orders and Matrimony. And by living lives worthy of him, holy and blameless, he would take us to his Glory, for ever and ever.
As for Luther’s, he attacked God’s holy Church, and picked and chose among what truths and beliefs of the Church he liked, and feeling his own guilt and blemish and inability to work out his salvation in the Church, 1,500 years after God founded his Church, Luther said all that was necessary was to believe, and sin to your heart’s content, cause God saved you once for all, Once saved, Always saved, and there was little you had to do to claim the Reward of eternal life.