The thing about the Pharisees is that they added their own rules to Old Testament law, making it way more difficult to follow. The Pharisees’ legalism could reach ridiculous levels. For example, on the Sabbath they’d determine if people underneath a collapsed house were in “dire need” or not … and if not, they’d wait until the Sabbath was over before helping them in order to avoid doing work. In short,  a Pharisee-like mindset is dangerous and can lead others astray.