Speakin' just for me, I don't understand why an electric guitar in church would be 'sacrilegious' while an acoustic one would be 'righteous'-- unless of course you mean my Seagull
. In the case of electrics, just use some sense-- avoid something shaped like the devil, a battle axe, a squashed spider or obscenely shaped.
I don't recall hearing too much flack about guitars in a church service.