I'm sure you're right in your observation, supra. I'm not so sure that we frail human creatures are always so good at identifying which is true and which is false. For instance, I'm reminded of the parable of the wheat and the tares. As well as the sourcerer who was casting out spells "in Jesus' name; without looking it up, Jesus' response was something along the lines of "He who is not against us is for us." Not to mention the parable of the sower, which tells us that it is our job to cast out the good seed, but that the harvest is the responsibility of God.
All things considered, I believe I would rather do and say things that tend to build up the body of Christ, even if an occasional false "tare" is roped in, than to do anything that would tend to tear down the body of Christ for fear that I would chase the wrong person away.
Peace.
One of those listed has, as a central belief, the teaching that "As man now is, God once was. As God now is, man shall become." I think this qualifies as a false gospel. And I feel fully qualified to call it such. More examples could be cited.
I have read much CS Lewis, but not recently, and I cannot claim to be a Lewis scholar. He is a superb apologist for the Christian faith, in my opinion. (He even defended the idea of purgatory.) I am currently re reading the fiction of JRR Tolkien, very close friend of Lewis, and instrumental in bringing Lewis to Christ. Tolkien was a robust Catholic.