Is there a halachic issue with invoking the name "Peter," or, as is more commonly used, "oh, for Pete's sake!," which I assume is a reference to Saint Peter. Wikipedia agrees with this conjecture, albeit without a source; see also "Oh, for Pete's sake!" on English.SE
As far as I know, nobody treats Peter as a deity, but he is a saint. Is there an issue with saying "oh, for Pete's sake!," due to his being a saint?
Referring to the names of men or women made deities is not problematic. See Shulchan Aruch Yoreh Dei'ah 147:2. The problem is that Beis Yoseif there quotes Rabeinu Yerucham (TAvC 17:5 [159c]) who understands from Avi HaEzri that one may mention the names of Christian so-called 'saints' themselves but may not mention them with any language of honor. This would preclude the title of 'Saint' before the names of these individuals. Exclamations like 'For Pete's sake!' are technically referred to as oaths in language, for all such exclamations are meant to invoke Heaven, Hell, or deity. Hence, I would consider it inadvisable to use such an expression for the usage itself conveys an implied reverence which is inappropriate.
