Luke 17:21 - Ellicott's Commentary On The Whole Bible

The kingdom of God is within you. — The marginal reading, “among you.” has been adopted, somewhat hastily, by most commentators. So taken. the words emphatically assert the actual presence of the Kingdom. It was already in the midst of them at the very time when they were asking when it would appear. The use of the Greek preposition is, however, all but decisive against this interpretation. It is employed for that which is “within,” as contrasted with that which is “without,” as in Matthew 23:26, and in the LXX. version for the “inward parts,” or spiritual nature of man, as contrasted with the outward, as in Psalms 103:1; Psalms 109:22; Isaiah 16:11. It was in that region, in the life which must be born again (John 3:3), that men were to look for the kingdom; and there, whether they accepted it or rejected it, they would find sufficient tokens of its power.