Mark 9:42-48 NLT
 “But if you cause one of these little ones who trusts in me to fall into sin, it would be better for you to be thrown into the sea with a large millstone hung around your neck. [43-44] If your hand causes you to sin, cut it off. It’s better to enter eternal life with only one hand than to go into the unquenchable fires of hell with two hands. [45-46] If your foot causes you to sin, cut it off. It’s better to enter eternal life with only one foot than to be thrown into hell with two feet.  And if your eye causes you to sin, gouge it out. It’s better to enter the Kingdom of God with only one eye than to have two eyes and be thrown into hell,  ‘where the maggots never die and the fire never goes out.’
This is a warning! Jesus warns against false teachings that cause believers to sin.
Throughout history there have been all kinds of false teachings. We need to beware and be careful that even our actions that teach others do not cause harm, especially to other believers.
Jesus goes on to say that some pretty severe action is required on our part to be sure we are not falling into sin ourselves. Jesus is the answer—Always! We go to Him for help in all things!