For Easter, we're singing a version of "Christ the Lord is risen today" that uses Wesley's lyrics mostly, including archaic verb forms such as hath. In the trumpets-and-elephants finale, however, the lyrics written by the composer employs has. Likewise, I've seen too many anthems and even modern hymns that mix forms of thou and you.
Even when they stay within a modern idiom, they'll use transitive verbs in an intransitive way (i.e., lacking a direct object). In our Christmas cantata last December, I think there was a noun ending in -es that was used as a verb; it rhymed well, but made no sense.
And don't even get me started on their theology (that would be Pet Peeve #247-b).