"superstition that" is correct and usable in written English.
You can use it to introduce a clause that describes a superstition. For example, "I believe in the superstition that if I carry a lucky penny, I'll have good luck."
It's not just a superstition that reheated dishes often taste better.
His attitude reflects an element of superstition that is inherent to sports, perhaps more than to other phases of life.
It too often twists reasonable and helpful faith into narrow superstition that may pose as the one and only true religion.
His jersey was too big for him, so he started to tuck in the right side of it, a superstition that stuck with him throughout his career.
Tradition has claimed that the most important achievement was the rounding of Cape Bojador in 1434 by Gil Eanes, who overcame a superstition that had previously deterred seamen.
Freud, the essential Enlightenment figure, meant for psychoanalysis to free man from the elements (the unconscious, superstition) that deprived him of autonomy.
"No," Kariya said, with a tight smile and a rap of his knuckles on a nearby wooden shelf, the common superstition that is thought to bring good luck.
The oral traditions and folklore of Zennor emphasize the importance of witchcraft and superstition that are in part founded on the wildness of upland summits and stormy coastline.
The medieval period is frequently caricatured as a "time of ignorance and superstition" that placed "the word of religious authorities over personal experience and rational activity".
It's deeply regrettable that the right wing has put a fundamentalist in the White House, given the whiff of apocalyptic superstition that now hangs over it.
Sure, it was an ancient superstition that bad luck would soon follow if the groom saw the bride in her gown before the wedding.
