Q: Is it sinful to follow a wrong Math-hab? I was wrongly practising as Hanafi but now found I'm Shafi.
A: It is not a sin to follow a math-hab. In fact, it is an obligation, for without following a math-hab one cannot truly practice on the Laws of Islam. All four Math-habs are Haq or true, so whichever one you follow will lead you to Allah. For this reason, you were not wrong in practicing on the Hanafi math-hab, but if you were a Shaafi'ee then it is better that you revert to your original math-hab, provided you have an Aalim available who can teach you the Shaafi'ee math-hab.