John 17:22... that they may be one, even as we are one: 23 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.
Believers are to have the same unity of purpose as Christ and his Father.
1 Corinthians 12:12 For as the body is one, and hath many members, and all the members of that one body, being many, are one body: so also is Christ. 13 For by one Spirit are we all baptized into one body, whether we be Jews or Gentiles, whether we be bond or free; and have been all made to drink into one Spirit.
We are to have one way of thinking – that of doing the will of God and not our own will.
John 8:29 And he that sent me is with me: the Father hath not left me alone; for I do always those things that please him.
Mark 3:35 For whosoever shall do the will of God, the same is my brother, and my sister, and mother.
John 14:23... If a man love me, he will keep my words: and my Father will love him, and we will come unto him, and make our abode with him.
Romans 8:9 But ye are not in the flesh, but in the Spirit, if so be that the Spirit of God dwell in you. Now if any man have not the Spirit of Christ, he is none of his.
Ephesians 3:17 That Christ may dwell in your hearts by faith; that ye, being rooted and grounded in love,
Ephesians 4:1 I therefore, the prisoner of the Lord, beseech you that ye walk worthy of the vocation wherewith ye are called, 2 With all lowliness and meekness, with longsuffering, forbearing one another in love; 3 Endeavouring to keep the unity of the Spirit in the bond of peace. 4 There is one body, and one Spirit, even as ye are called in one hope of your calling; 5 One Lord, one faith, one baptism, 6 One God and Father of all, who is above all, and through all, and in you all.
7 But unto every one of us is given grace according to the measure of the gift of Christ. 8 Wherefore he saith, When he ascended up on high, he led captivity captive, and gave gifts unto men. 9 (Now that he ascended, what is it but that he also descended first into the lower parts of the earth? 10 He that descended is the same also that ascended up far above all heavens, that he might fill all things.) 11 And he gave some, apostles; and some, prophets; and some, evangelists; and some, pastors and teachers; 12 For the perfecting of the saints, for the work of the ministry, for the edifying of the body of Christ: 13 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: 14 That we henceforth be no more children, tossed to and fro, and carried about with every wind of doctrine, by the sleight of men, and cunning craftiness, whereby they lie in wait to deceive; 15 But speaking the truth in love, may grow up into him in all things, which is the head, even Christ: 16 From whom the whole body fitly joined together and compacted by that which every joint supplieth, according to the effectual working in the measure of every part, maketh increase of the body unto the edifying of itself in love.
Colossians 3:16 Let the word of Christ dwell in you richly in all wisdom; teaching and admonishing one another in psalms and hymns and spiritual songs, singing with grace in your hearts to the Lord.
Colossians 4:12... always labouring fervently for you in prayers, that ye may stand perfect and complete in all the will of God.
Aspects of the unity of Christ and his church were dealt with in a previous question.
It is foreshadowed in the marriage union of man and wife.
Ephesians 5:31 For this cause shall a man leave his father and mother, and shall be joined unto his wife, and they two shall be one flesh. 32 This is a great mystery: but I speak concerning Christ and the church.
Marriage is the union of two in a common purpose.
Philippians 3:16... let us walk by the same rule, let us mind the same thing.
All members of the body of Christ are to have a common purpose.
Psalms 133:1 Behold, how good and how pleasant it is for brethren to dwell together in unity!
I hope you have found this helpful.