We have one or two religious very small communities similar to the Amish in the USA where it might be used. And we have the "Holier than thou!" type expressions. But in normal speech, no. In the bible, and historical novels, yes, but not down the supermarket or in the pub! Dost thou agree, 'tis archaic?

I recently watched the British film Kes for about the 10th time, which is set is Barnsley, South Yorkshire in the UK. The film was released in 1969 so quite a long time ago now. Throughout that film you can hear people use words such as 'tha' and 'thee'. I assume 'tha' is their pronunciation of the word 'thou'. It is a hard film to understand even for native English speakers from the UK, let alone non-Brits or non-native speakers because they speak in such broad dialect. My dad grew up in Yorkshire and he reckons using such words as 'thou', 'thee', 'thy' etc, which are completely antiquated in modern English are still a feature of certain South Yorkshire dialects. And that film shows this very clearly. But in English as a whole, these words are no longer used outside of certain set expressions such as 'holier than thou'.

I have heard that "thou" is still used in a few areas of England and Scotland, and among some of the Amish living in the American State of Pennsylvania, but cannot vouch for that from personal knowledge. I personally have NEVER heard anyone use "thou" in conversational speech. You will encounter the pronoun "thou" in some versions of the Bible, and in classical literature. It is quite possible that a person addressing God would adopt the Biblical style of speech for the purpose of his prayer, and therefore address Him as "Thou".

In Britain at least, "thou" lives on in some well-used idioms, such as: "holier than thou", "methinks thou dost protest too much" There are a number of idioms, mainly from Shakespeare and the King James Bible that use archaic words such as "thee", "thy", "thyself", "thine" or the -th for the 3rd person singular e.g. "maketh".

No, it is no longer used in modern English. You can find it in old English literature, and in some versions of the English bible. However that form of speech is now considered archaic.