Doing something Haram doesn't make people Kuffar. You don't know when they will make Tawba, or when God will lead them to the right way.
Saying about a person a Kafer is not an easy thing, due to this site: if one says about his brother a Kafer, then he is too. (I know this is outsinde the question, just for clarification).
However a person doing something Haram, and saying it is Halal, it is either ways. The first one isthat he doesn't know Halal from Haram and needs someone to sit with him and teach him, or he is really leaded by Satan and needs someone to take by his hand and make him do Tawba, after being convinced because
"There is no compulsion in religion" (2:256).
As a conclusion if a person is making something Haram, so we can say he is making something Kufur, but we can't say Kafir about him, especially if he still believes that there is no God but Allah.
اذا قال أحدهم أن السرقة لا عيب فيها، بينما كلنا يعلم أن السرقة حرام، فهذا العمل يكسب عليه سيئات، وعليك بنصحه. فإن لم ينتصح فدعه لله.
ولكن لا نقول أن هذا العمل كفر أو لا، الا اذا كان في العمل إشراك لله، ولكن نقول حلال أو حرام.
This reference has the thing s mentioned above about saying that robbery is Haram but not Kufr.