I was brought up 'brethren.'

They do not like to call themselves a denomination just simply Christians who gather to the name of the Lord. All in brethren circles would hold to classic dispensationalism, most (at least in N. Ireland) are not Calvinistic but a few are. In fact as I was growing up Calvinism was viewed as completely against what the scriptures taught.
Having said that many of the founding members of brethrenism were calvinistic, e.g. JN Darby (who was also a peadobaptist).
They hold the KJV in high esteem, some as if it were an original manuscript. If you’re not premill they would almost view you as being unorthodox.

Having said all that, and although theologically I have nothing really in common with them, they are among the most godly people I know; who have a zeal for the gospel that puts me to shame. They also show each other Christian love and fellowship that is not at all common today.

Hope that helps.

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Stephen Spence

A Presbyterian attending a Baptist church