(1) "In essentials, unity, in non-essentials, liberty, in all things, charity." (Rupertus Meldenius)
(2) "It would be strange indeed the Church should require more than Christ himself did, or make other conditions of her communion than our Saviour did of discipleship... Without all controversy, the main inlet of all the distractions, confusion, and divisions of the Christian world hath been the adding of other conditions of Church-communion than Christ hath done." (Edward Stillingfleet, Dean of St Paul's London, 1659)
(3) "From cowardice that shrinks from new truth / From laziness that is content with half truth / From arrogance that thinks it knows all truth / Dear God of truth, deliver me!" (author unknown)
These are three great quotes for anyone in leadership who cares about unity.