But the Lord is faithful. — It must not be thought from this that the word “faith” in the previous verse meant “fidelity.” St. Paul, after his favourite manner, is playing upon two meanings of the word: “But whether men have faith or not, the Lord is faithful.” There is the same play of words in Romans 3:3. “The Lord” seems here to be used, as was said on 1 Thessalonians 3:12, without distinct reference to one Person of the Holy Trinity rather than another. This characteristic of God is named because God stands pledged to all who believe in Him.
Who shall stablish you. — How soon St. Paul reverts from his own needs to theirs! He does not continue, as we should expect, with “who will preserve us”
Keep you from evil. — Rather (probably), from the Evil One, as in the Lord’s Prayer. Possibly, the word is used not without a reference to the word rendered “wicked” in 2 Thessalonians 3:2, with which in the Greek it is identical.