[NYer]

If we are going to reunite all Christians, why start with Orthodox? There are many more non-catholic churches in the world. Why bother so much about Orthodox Christians?

Catholics and Orthodox are the closest, doctrinally.

[Tantumergo]

"Catholics and Orthodox are the closest, doctrinally."

Technically you are correct, but in mentality Bible-believing Protestants are the closest to us. They are far closer to us than we would care to admit and they are far more Catholic than they would care to admit.