What Was Luther Right About?

On one of my last posts on Lutherism (Not Lutheranism) I quoted Dr. Luther in his response to Pope Leo upon discovering he was being officially excommunicated. One of his responses was this:
“If this bull* ( Papal Bull of excommunication) has come out in your name, then I will use the power which has been given me in baptism whereby I became a son of God and co-heir with Christ, established upon the rock against which the gates of hell cannot prevail. I call upon you to renounce your diabolical blasphemy and audacious impiety, and, if you will not, we shall all hold your seat as possessed and oppressed by Satan, the damned seat of Antichrist; in the name of Jesus Christ, whom you persecute."

Dr. Luther reveals in this statement that he indeed believed that baptism made him a son of God and co-heir with Christ! He believed that his infant baptism was regenerational as the Catholic Church has taught and believed since the early church came into being.

Therefore, if Luther believed that baptism made him a son of God and co-heir with Christ, why do many modern Christians reject baptismal regeneration and believe it is symbolic or something "covenantal?"
     The argument that is put forward is that Luther wasn't right about everything. "We don't follw Luther, we follow the Word of God."  But the reality is that Luther's new paradigm of sola scriptura was what every non-Catholic Christian follows and is a hallmark of their faith.
  How do we know Martin Luther was right when he came up with the other novel doctrines of faith alone, and scripture alone? (Of course Catholics believed we are saved by grace alone but we believe scripture when it teaches that our ultimate destiny is dependent on "what we did and didn't do" and we can't be saved by just faith alone) Could one of these other solas doctrines be wrong too?
    Was he wrong about his belief that the Eucharist was indeed the actual body and blood of Christ ?  There were several key doctrines that the founder of Protestantism held to that were distinctly Catholic. Yet soon after the reformation, one by one, Protestants picked and chose which doctrines they would hold to, which sacraments they could nullify, all based on their particular interpretation of scripture using Luther's principle of Sola Scriptura. Luther himself attempted to defend his belief in the Real Presence of Christ in the Eucharist going back and using Sacred Tradition and the Church Fathers because his sola scriptura principle did not help resolve the debate with Zwingli and other reformers.

So at the end of the day, one must reflect, what was Martin Luther right about and how do we decide?
To my Protestant friends, how do you decide which of Luther's doctrines were correct?
 Hint:    The answer is not  "The doctrines that align with my interpretation or my pastor's interpretation of the Word of God."


* Bull didn't have the connotation that is now associated with it as in the excrement of a Bos Taurus ( male cattle).  It meant a solemn letter of proclamation from the pope and was sealed with a piece of lead with the image of Peter and Paul on it. This piece of embossed lead was called a bulla, which my medical latin tells me is a raised fluid filled lesion. The papal bull was a raised slug of lead so the letters sealed with the bulla came to be known as Bulls.