The proof that that the world needs in order to believe in Christ is the unity of its members, the overcoming of divisions, the production of agreement and allegiance of all disciples.
According to Tino, this is a stronger interpretation because verse 11 also repeats the same: "that they may be one even as We are" where We = Father/Son = God/Jesus. And, oneness of nature with christ is convincing to the masses by personal testimony: seeing somebody be one with god causes someone to be compelled by their passion.
And, human minds can change on a dime. Nature is more immutable.