Start with you. Become well-informed by doing your homework. Formulate a plan. Research cults and coercive control. Don’t make the mistake of trying to rationally argue. Learn about mind control techniques and which communication strategies are most effective. Don’t fly blindly. [EDIT: Removed author's book shilling]
Build rapport and trust. Rebuild your relationship, if it’s broken. If you were the one to break contact, apologize. Reach out and be warm. Remember the good times. Focus on common values and areas you both enjoy (children, pets, music, dancing, fishing, sports). At first, don’t talk about controversial topics. Avoid “hot topics.” Just try to connect with the other person and have positive interactions. Build credibility and sustain positive interaction. Build a long-term relationship based upon respect, compassion, and love.
Do what you can to remove or minimize media that continually indoctrinates to only one point of view. This may only apply to certain types of cult groups. But it may be in the form of social media, videos, or television. You can even agree to make a pact to go on a media fast together. Don’t make this about “them” or “their problem.” Make this a fun thing to do together as a “break.” Be prepared to honor requests on your end.
Ask thought-provoking questions while being warm and curious. Be prepared to listen deeply. You will know if you have listened well if you can repeat back to them what they said. Be humble and open to hearing what they say.
Keep conversations positive, productive, and civil. Never get angry. Stay resourceful. It is better to end the interaction than to say something counter-productive. It is better to return to the conversation at another time, rather than the person cutting off all communication out of anger or fear.
Adopt a general tone of curiosity and interest in their positions. Pretend you’re an impartial counselor. Really try to get inside their beliefs.
Try to connect them with their authentic identity before these extreme beliefs. Remind them of past experiences together. Talk about the connection you once had and how you miss it.
Don’t “tell” them anything. Help them to make discoveries on their own.
Try to get them to look at reality from many different perspectives. This can include many things.
Teach them about indoctrination and mind control. Use examples for which they have no attachment.
Use examples of cult leaders with similar qualities to their group's leader(s) and have conversations about it.
Share feelings and perceptions, not judgments. Use “I feel” statements. Don’t claim to be “right.” Stick to what your perception is when reflecting back to them.
Ask a question and then wait for them to think and respond. Be patient. You do not need to fill silence.
Caution: an abundance of facts won't necessarily help. Do not overwhelm them with information, especially if it attacks the leader or doctrine.
Societal infrastructure and programs for cult-deprogramming would be great. Does anywhere have a successful version of these?