Christ did not found the heterodoxical RCC, which teaches many things contrary to Scripture, and adds to the word of God. Shameful.
But God DID found the Lutheran Church? Is THAT your assertion? If God did NOT found the Lutheran Church, why are you Lutheran?
It is arrogant in the extreme for your Church and the EO to think only THEY have the right to ordain priests/ministers, who then have the right to perform the Sacraments of Holy Baptism, and the Lord's Supper, and forgive sins "in the Name of the Father, and of the Son, and of the Holy Spirit." Jesus gave this authority to ALL the disciples to forgive or retain sins in John 20.
He did? My understanding was that he breathed the Holy Spirit not on ALL disciples, but only on those particular disciples who were present in the room.
In Matthew 28, the commission to preach, teach, baptize and make disciples is given only to the 11. This is then extended directly by God to Paul later on. When you read the Scriptures, particularly the book of Acts, you see that the apostles begin passing this commission on to their successors by the laying on of hands. This commission is not given in general to all believers.
Soooo...let us test something...my husband performed 3 marriage ceremonies in our church. He is a called and ordained servant of the Word in our church. Are those marriages invalid because he is not a Roman Catholic?
Yes it is valid, so long as it involves baptized Christians. Protestants are not bound by Sacramental Form when it concerns the Sacrament of Marriage. When Protestants want to convert, this is actually a hindrance sometimes--if they divorced and got remarried. It would just make things simpler if the RCC didn't recognize Protestant marriages, but no such luck. So in answer to your question, yes, the marriage is valid, assuming the couple is freely entering the marriage, etc.
If you knew Catholic theology you would know that Church teaching is that the couple themselves performs the Sacrament. The priest is just a witness. In fact, for the first 1200 years, the Church was not even directly involved in the Sacrament. The Church only became involved when it was necessary to bring order to what was a chaotic situation. The point is that it is that----it is not necessary to have a validly ordained Catholic priest perform the ceremony. Even in the modern RCC, the bishop can delegate a lay person to witness the marriage if there is no deacon or priest available in the area.