Extrapolating your argument, lets say for the sake of argument that Jesus declared that He was the truth. Based on your logic, Jesus claimed that He was useful. In fact, He was
the most useful way to God.
The argument, however, is this: Can any one ideology possibly be useful to
all?
When I use a word, Humpty Dumpty said, in a rather scornful tone, it means just what I choose it to meannothing more nor less.