Blind guides, you strain out the gnat but swallow the camel.
Here Jesus uses figurative speech to expose the absurdity of the Pharisees’ false faith. A gnat was a small and insignificant insect that, according to the Law, was forbidden to be eaten, and the Pharisees would even strain the wine, separating it from a gnat, so that by chance a gnat would not fall into the wine and they would not break the Law; or, if we interpret it allegorically, the Pharisees paid attention to the small details connected with the Law. On the other hand, they “swallowed the camel,” that is, they ignored the heaviest and most fundamental commandments of the Law. This expression symbolizes the disproportion of false faith: they were strict in small matters, but indifferent toward great sins. Jesus calls them “blind guides,” because they did not see the difference between what is important and what is insignificant, and what is worse, they were also leading people with the same delusion.