thou art = you?

The second person singular is not used any longer in English, but remains with us in religious texts. The deity ("God") is addressed in the second person singular. Otherwise, the second person singular is effectively dead, and there is only one second person, singular and plural--you.

A couple of conjugations:

I am
Thou art
He, she, it is
We are
You are
They are

I have
Thou hast
He, she it has
We have
You have
They have

The second person singular subjective is thou, the objective is thee and the possessives are thy and thine. ("Thy rod and Thy staff they comfort me." "For Thine is the power and the glory, etc. . . . ")

In some usages in England, especially in the midlands and the north, the common people used thee for both the subjective and the objective. This is seen most commonly in the continued use of the second person singular in dissenting religious sects such as the Society of Friends (the "Quakers") and their offshoots, such as the Shakers. The less well educated or the uneducated in those dissenting sects made no distinction between the subjective and the objective second person singular, and used "thee" for both.

Thanks.