“Despite the well-meaning Bible dictionaries that attempt to link this parable to various flora of the Middle East, the common mustard plant grows as a small bush, and is hardly the haven for birds. Furthermore, the identity of the birds have already been revealed in verse 19 (cf. v.3): the ministers of the “Wicked One!” This seems to portray a view in which the church will grow into something never intended–a monstrosity in which the very ministers of the wicked one will find refuge in its branches!” -Chuck Missler