Fun fact: “thee” and “thou” are the informal of “you” or it was until it was stopped being used
This is correct!
But originally, ‘thou’ was the singular second person pronoun, and ‘you’ was for a group of people, i.e. ‘you all’. ‘Thou’ came to be the informal version of ‘you’, that was used for talking to intimate acquaintances, those that are lower than you in rank, and those you look down on.
Love/intimacy: ‘all my fortunes at thy foot I’ll lay, / and follow thee, my lord, throughout the world’ (Romeo and Juliet 2.1.190-191)
To a social inferior: ‘Kent, on thy life, no more.’ (King Lear 1.1.155) Lear reasserting his rank.
So you can start a fight by thouing someone too much. Thus Sir Toby tells Sir Andrew to write a rude letter in which ‘if thou ‘thou’st’ him some thrice, it shall not be amiss’ (Twelfth Night III.ii.41-2).
Here’s a useful table I made:
Consequently, the reason ‘thou’ is used for God is because God is meant to be close to one’s heart/ It’s a sign of intimacy rather than casualness or inferiority.
In some rural areas of North England there are places that use a form of ‘thou’ 😉
¯_( ಠ_ಠ)_/¯ 