His invective was only a shade less virulent than was that of his opponent.
The substance of the controversy was far from being the straight alignment between reason and tradition that it has sometimes been represented as.

Both sides assumed the inerrancy of Scripture and appealed primarily to the same biblical arguments.

Luther had no difficulty in proving that the words "hoc est corpus meum" meant that the bread was the body, and he stated that this must be so even if contrary to our senses.

Zwingli had no difficulty in proving that the thing itself was impossible, and therefore inferred that the biblical words must be explained away as a figure of speech.

In a long and learned controversy neither side convinced the other, but each became so exasperated as to believe the other possessed of the devil.