17. But God be thanked, that ye were the servants of Sin--that is,
that this is a state of things now past and gone.
but ye have obeyed from the heart that form of doctrine which was
delivered you--rather, "whereunto ye were delivered" (Margin), or
cast, as in a mould. The idea is, that the teaching to which they had
heartily yielded themselves had stamped its own impress upon them.
JFB.
Picture Study Bible