I add 'for them' to complete the sense. I have doubted as to this passage. The word translated 'shine forth' is only found here in the New Testament and generally means 'to see,' or 'discern.' If this be the meaning here, we should read 'so that they should not discern the shining forth of the glad tidings of the glory of Christ, who is the image of God.'
'Grace abounding through the many.' The grace of God, perfect in itself, multiplies itself in its objects, so that thanksgiving abounds. Paul was delivered, but everything was for the assembly. It was not therefore merely a benefit to him, but still more to all, so that the grace or benefit was multiplied, and caused thanksgiving to abound to God's glory. The form of thought is peculiar, but the sense plain and striking.