The Reformation was, first and foremost, all about the Gospel of Jesus Christ. It was then, and it still is now. The task of reformation never ends, for every person, in every generation, needs to hear the good news of their Savior from sin and eternal death.
Perhaps Christianity has never been explained more simply and eloquently than in the words Martin Luther wrote to explain the Apostles’ Creed. Here is his timeless explanation that is a superb summary of what the theology of the Reformation was all about then and is all about today.
I believe that God has made me and all creatures; that He has given me my body and soul, eyes, ears, and all my members, my reason and all my senses, and still takes care of them. He also gives me clothing and shoes, food and drink, house and home, wife and children, land, animals, and all I have. He richly and daily provides me with all that I need to support this body and life. He defends me against all danger and guards and protects me from all evil. All this He does only out of fatherly, divine goodness and mercy, without any merit or worthiness in me. For all this it is my duty to thank and praise, serve and obey Him. This is most certainly true.
I believe that Jesus Christ, true God, begotten of the Father from eternity, and also true man, born of the Virgin Mary, is my Lord. Who has redeemed me, a lost and condemned person, purchased and won me from all sins, from death, and from the power of the devil; not with gold or silver, but with His holy, precious blood and with His innocent suffering and death, that I may be His own and live under Him in His kingdom and serve Him in everlasting righteousness, innocence, and blessedness, just as He is risen from the dead, lives and reigns to all eternity. This is most certainly true.
I believe that I cannot by my own reason or strength believe in Jesus Christ, my Lord, or come to Him; but the Holy Spirit has called me by the Gospel, enlightened me with His gifts, sanctified and kept me in the true faith. In the same way He calls, gathers, enlightens, and sanctifies the whole Christian church on earth, and keeps it with Jesus Christ in the one true faith. In this Christian church He daily and richly forgives all my sins and the sins of all believers. On the Last Day He will raise me and all the dead, and give eternal life to me and all believers in Christ. This is most certainly true.
From the LCMS website