Every believer thinks his faith is the true.
You wrote:
“Lutherans have always admited that the Lutheran Church is the true church. Only non-Lutherans have denied it.”
Actually, most Lutherans believe they are part of the true church which is invisible. They would say it is about the individual’s faith in Christ and NOT really about the Lutheran church per se.
As a Lutheran minister said a few days ago:
“No one has the lock on the truth just because of a title or name,” said the Rev. David Eberhard, pastor of Historic Trinity Lutheran Church in Detroit. “I think that it’s a step backward for the Roman Catholic Church. The term Catholic is not the sole property, ownership and title of the Roman Catholic Church. It is a universal church that believes in Jesus Christ as the savior.”
See what I mean?
http://www.detnews.com/apps/pbcs.dll/article?AID=/20070712/LIFESTYLE04/707120380/1041