You are quite right, we are not miles apart.
However, it is not an unserious matter to lay upon God the responsibility for consigning some to perdition. Fundamentally, that contradicts what His own word says of Him, that He would have ALL men to be saved and to come to the knowledge of the truth. That is my problem with Calvin. He is simply wrong in this, and in being wrong impugns the honor of God, which itself goes against the first and great commandment, whether enumerated as among two or ten others. In so saying I realize well that no Calvinist is Calvin. There are degrees. Just as not every papist is the pope. There are degrees. I choose to err on the side of the gospel in assuming anything about who is who. Since it is, according to His own word, God’s prerogative to settle final accounts, I gladly leave it to Him.
One last thing. The chief attribute of God that Calvin would emphasize, is exactly that which you have stated, that is, His sovereignty. That skews one’s theology one way or the other. Lutherans would say no, this is skewed in the wrong direction. They would say, for example, look at what God is being praised for by the host of heaven above all other things, all other of His attributes, in the book of Revelation (as everywhere else in the Bible). It is not His sovereignty, but His grace and mercy. This is fundamental to both Lutheran theology (and soteriology) and to the very confidence you rightly sense in Luther vis-a-vis God. Yes, God is sovereign, of course. But His grace and mercy is what draws us to Him. “For God so loved the world that He gave His only begotten Son ... “ is the best known and loved verse of the Bible for so many reasons, not least of which is the fact that His own Holy Spirit has led so many to love and treasure this cardinal truth.
Blessed Sunday to you, FK.
Very Orthodox.