[pinkpanther]

I'm just asking you a question.

Show me any Hadith that says I can lie when I'm doing dakwah, or as you put it, "advance Islam".

Taqiyya - Saying something that isn't true as it relates to Muslim identity (i.e whether one is a Muslim or what that means).  This is a Shiite term: the Sunni counterpart is Muda'rat.

Kitman - Lying by omission. An example would be when Muslim apologists quote only a fragment of verse 5:32 (that if anyone kills "it shall be as if he had killed all mankind") while neglecting to mention that the rest of the verse (and the next) mandate murder in undefined cases of "corruption" and "mischief."

Tawriya - Intentionally creating a false impression by saying something that is technically true, when knowing that the listener will interpret it in a different way.  This practice has a broader application than taqiyya.