If you just review their FAQ http://desteni.co.za/faq#8 you will quickly find that they do wish to destroy your mind and replace it with something in their making:
"Therefore -- the key is to STOP, STOP every and all participation in the mind of ourselves -- and as I have explained, the mind has become everything of ourselves so therefore it is literally stopping everything of yourself. Because it is in our very permission of participation within and as the mind to which we have defined 'who I am' / Self that the mind exists. Therefore in stopping participation in it -- it cease to exist and I is realized."
This group is a perfect example of how you can take nonsense logic and create anything you want. For them it is totally logical that 2+2=Cosmic Portal.