Along with perfect love, one of the central philosophies of Wicca. Perfect trust corresponds to the elements in one's life and environment attributable to the God. It can be summed up as unconditional recognition that everything happens for a reason. People (or things) are going to do what they do.
Perfect trust is not blind trust. A Wiccan isn't going to walk into a dark alley and trust that nothing bad will happen. Yes, the witch perfectly trusts a criminal; the witch recognizes that the criminal will, if given opportunity, will commit a crime. But because the witch does not trust the criminal, the witch keeps a highly-trained attack cat or a firearm and keeps the doors locked at night. And because the witch perfectly trusts the criminal, he or she knows that the criminal isn't going to change purely due to external influences. People aren't going to change merely because someone else wants them to; change must come from within.
Perfect trust is something to be striven for, but is unattainable on this plane of existence. We are human, and therefore are not perfect, but the effort to exhibit perfect trust leads to our spiritual growth.
"In perfect love and perfect trust"