Jesus prays for unity, John 17:11,20-23 - And now I am no more in the world, but these are in the world, and I come to thee. Holy Father, keep through thine own name those whom thou hast given me, that they may be one, as we are...Neither pray I for these alone, but for them also which shall believe on me through their word; 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. And the glory which thou gavest me I have given them; that they may be one, even as we are one: I in them, and thou in me, that they may be made perfect in one; and that the world may know that thou hast sent me, and hast loved them, as thou hast loved me.
An apostle exhorts to unity, I Corinthians 1:10 - Now I beseech you, brethren, by the name of our Lord Jesus Christ, that ye 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.
The Lord's supper expresses unity, I Cor. 10:17 - For we being many are one bread, and one body: for we are all partakers of that one bread.
Seven ONES and unity, Eph. 4:3-6 - Endeavouring to keep the unity of the Spirit in the bond of peace. There is one body, and one Spirit, even as ye are called in one hope of your calling; One Lord, one faith, one baptism, One God and Father of all, who is above all, and through all, and in you all.
Spiritual gifts tend toward unity, Eph. 4:11-13 - And he gave some, apostles; and some, prophets; and some, evangelists; and some, pastors and teachers; For the perfecting of the saints, for the work of the ministry, for the edifying of the body of Christ: Till we all come in the unity of the faith, and of the knowledge of the Son of God, unto a perfect man, unto the measure of the stature of the fulness of Christ:
Submission and unity, Eph. 5:21 - Submitting yourselves one to another one to another in the fear of God.
"We are not our own" -- and are not alone -- but part of a community of believers whose minds and hearts should be on one another. Consensus decision-making seems to fit best with the New Testament concepts of unity and one-anothering (as opposed to other forms of decision-making/governance that have been set forward for the church).