"That they all may be one" (Greek: ἵνα πάντες ἓν ὦσιν, ina pantes hen ōsin, Latin: Ut ūnum sint) is a phrase derived from a verse in the Farewell Discourse in the Gospel of John (17:21) which says:
that they may all be one. As you, Father, 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.