True, different from traditional Christianity but the same way the new testament church understood the Godhead.
I would have to assume that those not teaching this belief would lack the right foundation, etc. and therefore be quite unlikely to be among the “Church Jesus Built” per the UCG.
It's unknown. The general belief in United is that there are members of God's church in all organizations or at least future members of God's church. At the same time however it's understood that Satan has sway over the world including over some of those who are in United or other churches of God.
Of course I believe that the doctrine that the organization "United Church of God" embraces is the closest to biblical truth else I wouldn't attend services or fellowship there. But even living under completely false doctrine, such as Islam, doesn't exclude someone from God's kingdom. God can overcome anything when he calls people and he is eminently fair and loving.
'Tis an oxymoron you speak. :)
Of course God can overcome anything; but one of those things should not be wrong teaching by His Church.
I appreciate your reply very much.