What is the ruling on one who deems permissible the unlawful consumption of people's wealth, relying on man-made law that permits it?

If the questioner means, by those who unlawfully consume people's wealth, someone who resorts to man-made laws believing that it is permissible, then he commits an act of disbelief (kufr). However, if he means someone who is lax in this matter, without piety or shame, then he commits a major sin. And if he seeks assistance in this through man-made laws, without deeming them permissible or preferring them over Sharia, then that is another major sin.