The gospel of God which he promised beforehand through his prophets in the holy scripture, concerning his Son. Romans 1.1-3
You know the Gospel is nothing else but the proclamation of the one single person who is called Christ. Although at various times many other books have been written and many sermons have been preached people both heathen and Christians, and, indeed, even on the mother of God, St. Peter, the angels and many other saints, they are not Gospels. That only is the true Gospel which holds up Christ before us and teaches us what good we are to expect from Him.
At times the Gospel makes mention of John the Baptist, Mary and the apostles. But this is not the Gospel in the strict sense. Mention is made of these people to point out more fully whence Christ came and what His office is. What we read of John the Baptist ad the Virgin Mary in Luke’s Gospel is not written for their sakes, but solely for the sake of the person of Christ. Everything that is found in the Gospel is related to this person only.
In St. Paul’s epistles nothing is written about the saints; everything concerns Christ alone. The evangelists describe the miracles and wondrous signs that Christ performed. They do not describe a single work of John the Baptist or Mary. They are interested only in what Christ Himself achieved, how He helped people in body and soul, and how people became attached to Him as a result,
SL.XI.1834,1-2
PRAYER: We praise and thank you, heavenly Father, for the wonderful gift of your Gospel of salivation with its revelation of salvation in Christ alone. Implant your Gospel in our hearts in such a way that we really find Christ there, and cling to Him with all our hearts now and always, for His name’s sake. Amen.
Dr. P.D. Pahl Luther for the busy man: Daily Devotions from the Standard Gospels 385