partakers of Christ - (Compare Heb 3:1, Heb 3:6). So “partakers of the Holy Ghost” (Heb 6:4).
hold - Greek, “hold fast.”
the beginning of our confidence - that is, the confidence (literally, substantial, solid confidence) of faith which we have begun (Heb 6:11; Heb 12:2). A Christian so long as he is not made perfect, considers himself as a beginner [Bengel].
unto the end - unto the coming of Christ (Heb 12:2).