seeing that ye seek a proof of Christ that speaketh in me; who to you-ward is not weak, but is powerful in you:

since you are demanding proof that Christ is speaking through me. He is not weak in dealing with you, but is powerful among you.

since a proof ye seek of the Christ speaking in me, who to you is not infirm, but is powerful in you,

Since ye seek a proof of Christ speaking in me, (who is not weak towards you, but is powerful among you,