Certainly I agree with Cecil more than I would with Blackmore. One can simply reject certain thoughts, by a process similar to innoculation. "Get thee behind me, Satan!"
Unfortunately, other ideas or memes may be perniciously attractive, causing the mind to return to them over and over, like the tongue toying with a painful tooth. One wonders where the depraved maniacs who prey on children get their ideas originally, but clearly there is something in them which seeks the perverse attraction.
I am one of few who contend that ideas can be dealt with in a Skinnerian manner of avoidance therapy, but it would be costly. In my opinion less costly than allowing evildoers to molest unhindered, but costly in a number of ways.
Not only this danger, but others as well, may be so demonically appealing that they spell the end of civilisation, and there may be little that can be done to combat them. It could well be that for this reason, people tend to combine the forces of their ideas into defensible religious structures, similar to physical fortifications.
We are indeed, stronger together than we are on our own. Those of staunchly independent thinking should consider this occasionally.