That they all may be one; as thou, Father, [art] in me, and I in thee, that they also may be one in us: that the world may believe that thou hast sent me.
Note 108 at Joh 17:21: Jesus was praying that all believers would be one as He and the Father are one. This goes far beyond what many promote as unity today. Paul besought the Corinthians to "all speak the same thing, and that there be no divisions among you; but that ye be perfectly joined together in the same mind and in the same judgment" (1Co 1:10). This is God's standard of unity.
Note 109 at Joh 17:21: This oneness among the believers is what Jesus said would cause the world to know that Jesus is the Son of God. This is the greatest evangelism tool that the church has. Yet we pour millions of dollars and much effort into other evangelistic efforts while we are at each other's throats (see note 3 at Joh 13:35). When the church is one, the world will be won.