User blog comment:Bluefox87/One piece devil fruit name origins/@comment-5387880-20150718104539

There are 3 known important trees in the OP universe: 1) Tree of knowledge, t he Tree of Knowledge is a reference to the Tree of Knowledge in the bible which is said that Adam and Eve ate from (when told not to) and gained the knowledge of Good and Evil.(from the trivia)

2) Tree of Adam,  The Adam Tree is most likely a reference to the bible story of Adam and Eve with the Tree of Knowledge.(trivia)

3) Sunlight Tree Eve,  The names " Adam " and " Eve " were supposed to be the names of the first two humans, according to biblical text.(trivia)

So it is logical to assume that the reason they are called Devil fruits is because they were/are produced by the 4)Devil Tree, also a bible reference.

There will be also a 5)tree of life but thats another discussion.

this theory belongs to  Alpha2late17