As a Catholic, I heard the prayer “Our Father” frequently. However, there are many variations of the prayer Our Father. The most common one is the modern translation, “Our Father in Heaven, holy be Your name…”

Don’t know why, different area different style. I heard a weird version of “Our Father”, that is: “Our Father who art in Heaven, holy be Your name…”

Why I say it is weird? Have you read the words like: Thee, Thy, Thou, Thine and else? These are the archaic English, which means “You”.
thee = you
thou = you
thy = your
thine = yours
(Hope that I do not make it wrong…)
Check this: http://dan.tobias.name/frivolity/archaic-grammar.html