The unity of the saints is a unity that begins with the truth. There can be no unity with those who proclaim a false Gospel and another Christ. While all the redeemed are united in the faith of the Gospel, selfish ambition and conceit (including vain opinions) are enemies to the true unity of God’s people. As Paul makes clear in Philippians 1:15-18, it is possible to proclaim the truth in a spirit of rivalry. Thus, the vanity of such a person’s opinion may not be doctrinal but in the divisive pride of believing they have something of which to boast. Whatever gifts, abilities or understanding we have are gifts of God. This realization is what makes it possible for us to consider others more significant than ourselves.