Berean Study Bible
Brothers, stop thinking like children. In regard to evil be infants, but in your thinking be mature.

King James Bible
Brethren, be not children in understanding: howbeit in malice be ye children, but in understanding be men.

American Standard Version
Brethren, be not children in mind: yet in malice be ye babes, but in mind be men.

Darby Bible Translation
Brethren, be not children in [your] minds, but in malice be babes; but in [your] minds be grown [men].

Douay-Rheims Bible
Brethren, do not become children in sense: but in malice be children, and in sense be perfect.

English Revised Version
Brethren, be not children in mind: howbeit in malice be ye babes, but in mind be men.

Young's Literal Translation
Brethren, become not children in the understanding, but in the evil be ye babes, and in the understanding become ye perfect;