Here’s my favorite Jewish atheist joke, c/o Leo Rosten:
A brilliant young student goes to an old, learned rabbi and defiantly exclaims, “I must tell you the truth! I have become an apikoros. I no longer believe in God.”
“And how long,” asks the elder, “have you been studying Talmud?”
“Five years,” says the student.
“Only five years,” sighed the rabbi, “and you have the nerve to call yourself an apikoros?!…”
• Apikoros is a rabbinical term for unbeliever, skeptic, agnostic, atheist.
Marc Di Martino 
Yes, but it comes from Greek (same source as “epicurean” in English). The interesting thing is how it has become a verb in modern Hebrew. If someone says “hitpakarti” it could be like them saying “I wised up.” I don’t know whether any religious Hebrew speakers try to avoid using the word in order not to be seen as endorsing the equivalence between being atheist and having seen the light. I suppose it is at least theoretically possible that a Hebrew-speaking atheist turned believer might use it in the sense of having seen the light, without being really conscious of having turned the word’s meaning around 180 degrees.
I know about the word’s origins, but had no idea of its contemporary usage in Israel. That’s very interesting. Thanks, Stewart.
It gets even more interesting, because I searched to see if anyone else had commented on this usage and “hitpakrut,” which one could get from it, does exist, but it is not derived from epikoros. It comes from “hefker,” so the meaning is more like “abandonment.”
I’m following you, Stewart. So התפקרות would be the spelling? And אפיקורסות would be “Epicurianism/unbelief?” Does the latter exist in Israeli Hebrew?
This only gets more interesting. I’ll have to go to a proper book sometime, but firstly Hebrew Wikipedia (I’ll translate for others below):
התפקרות: ביטוי שנגזר מן המילה “הפקרות” (כלומר, חופש מוגזם, היעדר פיקוח), וככל הנראה גם מן השם אפיקורס[4] (פילוסוף יווני שתורתו הפכה סמל לחילוניות). ביטוי זה יוצר הקשר שלילי של אדם המבקש לצאת ממסגרת החוק והנורמות החברתיות. מילה זו מופיעה בשפה העברית כבר בספרות מתקופת התלמוד, אך מקובלת בימינו בעיקר בקרב הציבור הדתי והחרדי.
Hitpakrut: an expression coined from the word “hefkerut” (i.e., exaggerated freedom, a lack of supervision), and apparently also from the name Epicurus (Greek philosopher whose teachings have become a symbol of secularism). This expression creates a negative context of a person who wishes to exit the framework of law and social norms. This word already appears in Hebrew in literature of the Talmudic period, but is today mainly current among the religious and ultra-Orthodox.
Then there’s this from a language column in Maariv in 2009:
שוש מאזור המרכז כותבת: האם המילה “התפקר” באה מהמילה “הפקר”, או מהשם “אפיקורוס”?
“התפקר” ו”הפקר” באות מהשורש התלמודי פק”ר, שיש לגביו שתי השערות. אחת, שזהו שיכול של השורק פר”ק, כלומר, פורק עול מצוות ואמונה. השנייה, שיש כאן השפעה של המונח היווני אפיקורי, שפירושו אדם הכופר במוסכמות. המונח הזה התגלגל משמו של הפילוסוף היווני אפיקורוס.
Shosh from central Israel writes: Does the word “hitpaker” come from the word “hefker” or from the name Epicurus?
“Hitpaker” and “hefker” come from the Talmudic root ‘pk”r,’ about which there are two assumptions. One, that it is an anagram of the root ‘pr”k,’ i.e., throws off the bridle of mitzvot and belief. The second, that there is an inflience of the Greek term “epicurean,” meaning a man who violates norms. This term has developed from the name of the Greek philosopher Epicurus.
[me again] So, basically, the explanations that don’t involve anagrams all seem to go back to the same name. The usage I gave at the beginning in my first comment is just something I remember from everyday speech.
I’m starting to feel like I’m back in Ulpan. There must be some gematriya in all this, no?
“influence” – my typo
where it says “shorek” instead of “shoresh” is Maariv’s typo 🙂