There are both do's and don'ts when it comes to witnessing to cultists. Following are a few that I've learned over the years.
The first do is, do identify with the cultist. Convince him (or her) that you consider him to be a person in his own right -- worthwhile, basically honest, and not trying to put something over on you. Cultists are people before they're cultists. They have families, they have children, they have needs, they have frustrations and fears, and they are brothers and sisters in Adam, though not in Christ.
In Acts 17 we are told that all people are God's offspring. This means that in Adam, all of us share a common heritage. So let's talk to cultists from the family-of-Adam perspective, prayerfully hoping to bring them to the family-of-God perspective.
Second, do labor persistently with cultists. Never give up unless the cultist decisively refuses further contact. Until they pull the plug, we need to hang in there -- remembering that the Lord blesses His Word. The Scripture says, "My word that goes out from my mouth: It will not return to me empty, but will accomplish what I desire and achieve the purpose for which I sent it" (Isa. 55:11).
Third, do exhaust every effort to answer the questions of cultists. After we communicate the Gospel to someone, it's important for us to be prepared to give them reasons why we believe in it. The apostles were apologists as well as evangelists. They not only proclaimed Christ, but when they were questioned, they had good, solid reasons for their faith. That's why Peter said, "Always be prepared to give an answer to everyone who asks you to give the reason for the hope that you have" (1 Pet. 3:15).
Fourth, do allow the cultist to save face. When you're witnessing to a cultist and you've won the argument, you have an opportunity to present the Gospel to him in a very loving manner or you can come on so strong that the person will end up fighting you even though he knows in his soul that he's wrong. When you sense that the person -- a Jehovah's Witness, for example -- has lost the argument and is deflated, that's the time to be magnanimous and say to the person, lovingly: "I realize that we can get awfully uptight in these areas if we let ourselves. Let's just forget that you're a Jehovah's Witness and I'm a Baptist (or whatever you are). And let's just think of ourselves as two people who want more than anything else to know the whole truth and the whole counsel of God. Right?" I haven't met a cultist yet who wouldn't say "Right" in response. Then you can say: "You know, it isn't your fault." That is an important point to make. Because the real fault lies with the organization that's deceived the person, not with the person who's been deceived. The person you're speaking with may have bought the deception, but the Watchtower deceived him. Fix the guilt upon the organization. Then, as you continue sharing the Gospel, you may find that the person is a lot more open.
Now, there are also a few don'ts I want to mention. First, don't approach a cultist with a spiritual chip on your shoulder. A spiritual chip is the communication of the feeling that you are looking down on the cultist because you have something he or she doesn't have. Such an attitude will turn them off as fast as anything you could imagine.
Second, don't attack directly the founder of any particular cult. When I lecture on Mormonism, I do not attack Joseph Smith as a person. When I lecture on Christian Science, I do not attack Mary Baker Eddy. I criticize the theology they taught. Remember, if you deal in personalities, people become instantaneously defensive.
Third, don't lose your patience, regardless of how dense a cultist may be. Remember how dense you and I were -- until the Lord managed to break through. Because cultists are bound in the chains of slavery to sin, you need to be patient. And being patient means being willing to go over something ten times if necessary, believing that the Lord will bless your efforts.
In closing, let me say that after all is said and done, the way we most effectively communicate with cultists is through the agency of the Holy Spirit. Remember, it is He who touches their souls; it is He who convinces them of sin and of righteousness and of judgment (John 16:8). And we become in His hands the vessels which by grace have become fit for the Master's use.
For more of Walter Martin's work go to the Website hosted by his family: http://www.waltermartin.org/