Strange gods?

Genesis 35:2 says, “Then Jacob said unto his household, and to all that were with him, Put away the strange gods that are among you, and be clean, and change your garments:”  So, were Jacobs people worshipping other gods or were there other gods for real?  Why would Jacob’s people worship other gods if the god of Abraham was so powerful.  Maybe it was the slave women and children who were taken by Jacob’s sons who worshipped the strange gods. But the big question is why Jacob’s people had to be told by god to change their clothes.