How do we know that God didn't lie at Sinai? Maybe he said he was good and compassionate, and promised us reward, but it's all a trick? Why believe that God is true?
I've recently seen some events advertised for specific groups or for people who fit a certain description, and it got me wondering, would it be alright, from a Jewish perspective (Halachic, Hashkafic, ...
Can you pray something that isn't true or (at least) that the petitioner doesn't believe to be true?
In the Aruch HaShulchan OH 581:4, he writes regarding the selichos we recite before Rosh HaShanah: האחת: דאלו שאינם מתענים, ובהסליחה מוזכר לשון "תענית" או "צום" – לא יאמרו זה, דלא ליהוי כדובר שקרים. ...