I seriously doubt that we are going to find only Orthodox and Catholics in the next world. Our boys are in a joint Orthodox-Lutheran Scout troop and I think the Lutherans are awesome Christians. I fully hope to know them after this life as well.
Belonging to a Church (administratively) is not a ticket to a salvation. But that does not make every church equally valid, MarMema. A Church is not a club one can set up as he or she pleases. Lutheran Church was born out of a desire to purge the Church of some illicit human practices -- the end result was heretical theology with equally illicit human practices. I am not sure if you realize that the Lutherans were rebuked by the EP in the 16th century for their heresy. They may be individually awesome Christians, but that does not make their church a Church as far as I am concerned.