I don't believe you're listening ;-)
Read the class description. Under the forsake magic ability, it states that if a forsaker is tricked into using a magic item or using a spell ability of theirs, they lose their class abilities for a week. Furthermore, if they deliberately use said magic item or ability, they lose their class abilities for a year and a day.
So, if they use something without knowing, they lose their abilities for a week. It doesn't matter if they can't possibly know that it's magical...if they somehow benefit from a magic item, then they lose their abilities. If they *deliberately* use a magic item (notice, I'm in a new sentence now, and this has nothing to do with the other sentence), they lose their abilities for a year and a day.
Now, having restated myself almost exactly word for word, I will hope that you actually read the class (especially the "forsake magic" ability) this time before posting.
P.S. Turnabout is fair play...you treat other posters (and myself, in your post above) in this way when they don't read the rules before posting ("doing the research" i think is how you phrased it in a recent post in another thread), so I am simply doing the same. Usually, I do respect your opinions, but here you have clearly not read the rules and I thought I would point it out, flippantly mentioning that I get to prove you wrong since your opinion is held in such high regard here and so I thought it would be fun to point it out offhandedly, and in return I was confronted with what seemed like sarcasm and hostility...so that is my justification for the apparent hostility of the above post.
Edit: P.P.S. I decided to go ahead and post the relevant text of the ability, so as to clear things up a bit, hopefully.
Forsake magic: ....Any forsaker who unwittingly uses a magic item or casts a spell (under the influence of a charm person or dominate person spell, for example) loses all the special abilities of the prestige class for one week.
Later, in the section about Ex-Forsakers...
Any forsaker who willingly violates [the strictures of the prestige class] by using magic items or casting spells loses all special abilities of the prestige class and can progress no further as a forsaker. If he thereafter remains pure (uses no magic) for a year and a day, his abilities are reinstated at the previous levels and he may once again progress in the prestige class.