Edit: This is my 666th post on this blog.
You’d be surprised how late people were still using the pronoun thou in their non-liturgical prayers. Billy Graham used it at the 1989 U.S. presidential inauguration, and Martyn Lloyd-Jones in 1969. While no one will reasonably argue that this was the daily usage in these years, the effectiveness of these two men seems to have been unaffected by an arguably archaic usage.
This dignified yet intimate form, in my opinion, merits keeping in our prayer vocabulary. The King James Bible and the 1662 Book of Common Prayers do have some usages that by now are very difficult for most people to understand and so are best altered or glossed: some of these in the King James Bible are prevent (1 Th 4.15), ‘precede, go before, lead, anticipate’; let (2 Th 2.7), ‘restrain’; and conversation (Gal 1.13), ‘conduct’. Unlike these, thou does little if anything to hinder understanding – indeed, it fills a slot in an otherwise defective verbal paradigm. I find little reason, therefore, to purge it from public and private prayer.
One may find the use of thou to be odd, but even this oddness is no clear disadvantage to a praying Church that lives by different criteria from a world that pays homage to mammon and false efficiency and unsustainable novelty. Indeed, thou does not become archaic until, by some (probably ungodly) person’s measure, what the word expresses is obsolete; and until another way develops for saying the same thing, with the same distinctions, the only obsolescence for thou must be the obsolescence of the very idea that the word signifies.
Since thou is neither particularly hard to understand nor unrigorously to be labelled obsolete, I find nothing blameworthy in it. Unless further charges can be levelled against the word, then, I suggest that the English-speaking churches use it without apology. What do you think?