In John 17, Jesus seems to tie the unity of Christians to the world believing that He is truly sent from God. Jesus prayed: "My prayer is not for them alone (His first disciples). I pray also for those who will believe in me through their message, that all of them may be one, Father, just as you are in me and I am in you. May they also be in us so that the world may believe that you have sent me."
Here's a quote that expresses that idea in a practical and contemporary way: "If there is going to be real renewal, real revival there will have to be widespread repentance for how we have failed to answer Jesus' plea for demonstrable unity and grace among those who follow Christ." --James Emery White
Christ-followers are like the pieces in a mosiac. Each piece can only display a tiny part of the image. It takes all the pieces properly aligned by the artist, in order to see and appreciate the full image.
No single one of us can fully reflect the risen Jesus to the world. But when we all come together in the unity of heart-felt love, genuine humility, and Christ-led brotherhood (not mere formal or doctrinal unity), the image of the risen Jesus will be reflected in a such glorious way that the world can't deny Him.
In the first century, they said this about Christians: "How they love one another." And seeing that love in action, attracted multitudes of people to the risen Jesus.
It's like a piano. We individual Christians (and individual churches and denominations) are like the keys. If we all play our favorite key individually we will flood the world with noisy confusion. However, if we all allow the living, resurrected Jesus to "play" us, we will resound in beautiful harmony that reflects the glory of the Great pianist!
That's revival! So, let's reset to one and let the living Jesus do the rest!