There are some for whom evangelism of any measure or purpose is an utter affliction, this in spite of the strength or universality of the intended communication. The bible - notwithstanding its poetic use of metaphor - seldom fails to makes its point. This does not however imply that the cloak of design is entirely without uncertainty. Take for example the expression from Matthew 7:6.
Give not that which is holy unto the dogs,
neither cast ye your pearls before swine,
lest they trample them under their feet,
and turn again and rend you.