A good tree cannot bring forth evil fruit, neither can a corrupt tree bring forth good fruit.
All Commentaries on Matthew 7:18 Go To Matthew 7
Theophylact of Ochrid
AD 1107
A corrupt tree cannot bring forth good fruit as long as it is diseased. But if it has changed its condition, it can bring forth good fruit. See that He did not say, "it will not be able," but only that as long as it is corrupt it does not bear good fruit.
