You obviously didn't read the web link I provided. The greek spelling of Jesus that you provided through your IHS designation is inconsistent with proper Greek spelling.
From the site:
"Iesius or Ihsou? Ie... or Ih? A profound difference!
Contrary to popular belief, these two names at the beginning of this paragraph are NOT written in Greek letters! They are English equivalents of Greek letters! At the end of this paragraph there is the actual Greek lettering, and it's English counterpart. Note: There is no "e" in the biblical Greek spelling of the Savior's name, which is from the Hebrew, [wvwhy, "Yah'shua" [ihsou - Ihsou] (pronounced like "Joshua" with a "Y"2...). But...there IS an "e" in Iesius - IesiuH !"
Not necessarily. But then again, I know of no situation where any Biblical character, not one, at anytime, is referred to by just the first three letters of their name. Not one. Not even Jesus.
The point is here is that you are suggesting that Jesus is referred to by just the first three letters of His Greek name. There isn't one instance you can point to anywhere where it was common to refer to Jesus by just three letters in Christendom. Nowhere.
The Catholic church is the only one that does on a consistent basis as part of tradition and they are quite clear in their interpretation, however wrong it may be.