Because gives a reason. I did it because I wanted to. For has many definitions. One of them shows a purpose: I did it for that reason. (You could also say: I did it because of that.) As has several definitions. A common one is in the role of, or in place of. I used the piece of wood as a hammer to drive in the nail. The lady above gave a good answer regarding cause ('cause).

1. I went to a restaurant BECAUSE I was hungry. a. I was hungry. b. I went to a restaurant. 2. A bad man has broken into my apartment, FOR the door is broken. a. "For the door is broken" is my guess that a bad man broke into my apartment. b. Of course, a bad man did not break into my apartment because he wanted to break my door. (He broke into my apartment because he wanted to steal my computer.) 3. The mailman is not coming today BECAUSE January 1 is a holiday. a. It's January 1. b, There will be no mail delivery today. 4. I think that the neighbors are on vacation, FOR there are a lot of newspapers on their front porch. a. "For there are a lot of newspapers on their front porch" is my guess that my neighbors have left their house. b.Of course, they did not leave their home because there are a lot of newspapers outside. (They left their house because they went on vacation.)

I guess you are asking about when these are used in similar ways. As tumliner said, "as" has several uses. I stayed home because the weather was. I stayed home as the weather was bad. I stayed at home for the weather was bad. <-- Sounding a little like old English . Some answers will be complicated because "as" has many uses. Some answers will be complicated as "as" has many uses. . I stayed home 'cause the weather was bad. <-- As, MoiraWendy says,, this is used in novels & spoken language. Change it to because if you want to understand & speak well. . . Because these words have other uses, you may want to look them up. Because these words have other uses, you may want to look them up as well. As these words have other uses, you may want to look them up as well. "cause" is also a noun. Look it up . He answered as a teacher might, even though he had no training. (as = "in the same way", or "acting as" or "taking the role of") . The cause of the confusion was the reuse of many words for different purposes. The reuse of words for different purposes was the cause of the confusion. (cannot use because here: different use) The confusion happened because English reuses words for different purposes. . Because "for" has many uses, you should look it up separately. . As this is now done, I will stop writing. Because this is now done, I will stop writing. For this is now done, I will stop writing. <-- Wrong. Can't use it this way.

Because is sometimes abbreviated as 'cause in novels (or even as 'cos) because ('cause/'cos) it's the way we say it. So, do you mean 'cause or do you mean the word 'cause' as in the noun a cause. They are pronounced differently but I cannot type the phonetic alphabet here... so you will have to check your dictionary.