Lutheranism, like all other Christian Churches is a creation of man...yes, including the RCC!
Christianity is a state of the heart!
I know a lot of members of Christian religions who are not Christian...like my ex-Mother-In-Law, a staunch Catholic from Mexico, who drove her daughter over the edge to where she started to abuse our son, resulting in her arrest and the eventual divorce. A really devout Roman Catholic, but not very Christian.
I hope that explains it. I hope you are a Christian and not just a devout member of a man-adaptation and interpretation of Christ's teachings.
CAn one be a 'christian' while a devout MORMON?