Meaning of the word "iż"
I found this word (iż) in a prayer, and I was wondering about the translation of it:
"Spraw, by wszyscy ludzie poznali, iż w nim tylko jest prawda i zbawienie."
Dziękuję z góry!
That's a very bookish (seems almost archaic to me) version of "że". I like it personally, but you rather won't encounter it too often. Sometimes if you have a text with a lot of "że" the author can change some of them to "iż", as Polish generally tries to avoid repetitions.
It basically means "that", like "that" in this sentence: It was certain that he was going to make some great improvements". It has the same meaning as the common in everyday speech "że", but it is used in a very formal language, older books or documents.