The foolishness is because of a defect in the hearers, not in the speakers. The gospel is quite rational to rational people. Unfortunately, the unsaved are by definition irrational. Thus the rational gospel is foolishness to their (dead) ears.
Let's not loose track of your initial suggestion.
Since when did Christians like DeMar take it upon themselves to do the work of the Holy Spirit?
By this statement you were clearly insinuating that gibberish could come out of ones mouth and they would be preaching the gospel according to the will of God, since all one needs to believe is the Holy Spirit.
The wise crack backfired.
IIRC something like that happened on the day of Pentecost.