"delusion by" is grammatically correct and can be used in written English.
It typically means that something was caused by a delusion or false belief. Here is an example sentence: "His behavior was driven by a delusion by which he believed he was being followed by government spies."
The Growth Delusion, by David Pilling Tim Duggan Bookss).
Ian McEwan "The God Delusion," by Richard Dawkins; "Terrorist," by John Updike; "Everyman," by Philip Roth.
Next was "The God Delusion," by Richard Dawkins, an evolutionary biologist and Britain's preëminent science writer.
A New Post for Banks This week, Eric Banks reviews "The Science Delusion," by Curtis White.
Among the most notable of these was Darwin's Angel: An Angelic Riposte to "The God Delusion," by John Cornwell.
Cawley attempts to shock Teddy out of his delusion by enabling him to act it out in glorious detail.
However, for the economy as a whole, China's rising profits should promise more years of strong growth ahead.* "The World Bank's China Delusions" by Weijian Shan, Far Eastern Economic Review, September 2006.
Although the movie cleverly tricks us into sharing the character's delusions, by the end of the film its method of doing so has come to seem heavy-handed.
They justify their blindness, their convenient self-delusion, by telling themselves that Illinois needs more federal money -- the awarding of which is partly based on showing you've raised test scores -- in order to finance further reform that will have real teeth and meaning in it.
She confronted her obsessive delusions by giving them concrete form, ushering them from fantasy into reality by painting the abstract images everywhere she could.
While most UFO sightings are dismissed as delusions by crazy people, a Chicago Tribune reporter followed up on the story--and said seasoned pilots, airline management and mechanics all came forward, shaken by what they saw.
