HOW is Jesus in the world by the power of the Spirit? He's in the world by Spirit-empowered New Humanity, aka, the "Bride of Christ." The church is the visible, or physical body of Christ on this earth. We not invited to participate...we are that Body. And we're either telling the truth about who Jesus is by the way we love one another or we're telling a lie, in which case we need to repent. If I were an unbeliever and I saw the way the church was splintered over so many factions, i.e. denominations, age, race, etc. I would find it disgusting. A whole "body" is a beautiful thing. A splintered "body" is repulsive and gross. Who wants to be a part of that??? People are not flocking to the American evangelical church from outside because, quite frankly they find our lack of love for one another and lack of unity to be quite grotesque. Until the church in America, and other parts of the Western church recovers, one Lord, one faith, and one baptism, she's going to continue to have a "revolving door" type church membership.
The church is not the destination, the Kingdom of God is. But the church is the heart of that Kingdom, and in principle, she is already there. The world is groaning and longing to be changed and it is looking to us to see what that change looks like. The church alone has been given the message of the Gospel and it is that Spirit-empowered message which has the power to transform, (and is transforming) this world and making all things new.