Paul writes this way three times.
I appeal to you, brothers, by the name of our Lord Jesus Christ, that all of you agree, and that there be no divisions among you, but that you be united in the same mind and the same judgment.
Only let your manner of life be worthy of the gospel of Christ, so that whether I come and see you or am absent, I may hear of you that you are standing firm in one spirit, with one mind striving side by side for the faith of the gospel, and not frightened in anything by your opponents.
So if there is any encouragement in Christ, any comfort from love, any participation in the Spirit, any affection and sympathy, complete my joy by being of the same mind, having the same love, being in full accord and of one mind.
And Peter does so likewise once
Finally, all of you, have unity of mind, sympathy, brotherly love, a tender heart, and a humble mind. Do not repay evil for evil or reviling for reviling, but on the contrary, bless, for to this you were called, that you may obtain a blessing.
Not once, looking at the context, is it possible to find either Paul or Peter using this phrase to exhort everyone to adopt some sort of precise agenda that might justify the formation of a denomination. In every case, being of one mind means tolerating differences of opinion and being humble toward one another.
That’s how the New Testament speaks of “like-minded believers.”