Insha Allah – literally meaning “if God is willing” – is a word that is supposed to be used instead of saying yes (or no.) It is a bit confusing, but here is the thing; the believers of God wouldn’t want to show certainty of anything without God’s will. So previously, Insha Allah was to be used as a yes.
For example, you ask someone if they are going to do something, and they will do it, they would answer you “yes, insha Allah I will” – if God is willing I will do this.
However, with the change of times, insha Allah became an over used word. Being it a word that you cannot argue with, it is used when you want to say no in a nice way. It is a word you cannot argue with, because well, one would tell you “I cannot do it if God is not willing, so insha Allah! Don’t ask more than that.”
When I was young, I would ask my dad for some toy, or to go to some place, and he doesn’t want to tell me no so he wouldn’t upset me, he would say insha Allah…Well, with experience I came to understand that the word insha Allah would mean there is a high probability of not getting what I wanted 😀
The word originated in Egypt with the Islamic invasion. However, with the merging of the Coptic and Islamic Arabian cultures, the word became used by all Egyptians regardless of their religion. Because basically, Allah is the Arabic word for God whatever his name is, so it is used by both Muslims and Christians.
The practical note for you, when you are visiting Egypt or traveling through it, when someone says insha Allah, don’t count on them 100%, unless it is their job to fulfill your request! If it’s just a favor you are asking, it depends on the person, and it depends on how much you trust them in the first place. However, I have to add, as a foreigner you will most probably get what you requested anyway, as people won’t want to let a tourist down – don’t over use that 😉