"Take care that no one deceives you" [Mk 13:5]
Deception is a major component in the art of warfare. Being a "liar from the beginning", Satan is a master of deception. If our opponent can deceive us, he can get in much closer and secure a victory with far less effort.
Principles of Deception
The first principle of deceptions is “Get people to believe what they want to believe.” It is the first principle because it is the easiest and leads to trusting the deceiver, which makes further deception easier. So be aware of people who ‘do their homework on you’ or who are inquisitive about your likes and dislike. And be aware of what you want to believe and what you don’t want to believe.
The second principle is “Distract people from what you are doing.” Obviously conjurers do this by drawing your attention to one of their hands so that you do not see what the other is doing. We can be distracted in many ways, such as:
Others set the agenda of a meeting to skirt the issue, so that you think that you are the only one to think that something is important.
Wrongdoers accuse others of wrongdoing as a smoke-screen for their own wrongdoing. For instance the History Channel on TV has a lot of Hitler and Stalin documentaries to draw attention away from the International Bankers who funded both sides in WWII.
Humour is often used to distract from the seriousness of an issue.
The third principle is “Imitate the genuine article.” We have a natural inclination to think that if it looks right then it is right. It is only on closer scrutiny that we start to pick up the differences. For instance the maxim, “Charity begins at home” sounds very Christian, but it isn’t. It came from a pagan Roman philosopher who tried to undermine the effect of the Christian maxims, “Love your neighbour as yourself” and “Love your enemies”.
The fourth principle is “Plant false leads.” Some Secret Services have a reputation for doing this. They carry out covert operations with foreign equipment and speak in a foreign language so that another nation will get the blame. It is called “false flag” operations. “False labeling is another”. People will use one label, such as “women’s health”, as a cover for another, promoting abortion.
Principles to Counter Deception
Test everything and do what is right (i.e., in accord with the Gospel)
Analyse who benefits materially from a proposal; "Follow the money"
Be aware of emotional pressuring either as bullying or seducing.
Remember Satan gets good people to do good things (instead of doing the right thing).
Carrying out our Mission
The Church's mission is to bring humanity home to God. We need to remain aware that people are caught up in a web of deception. It is important for us to be transparent with them. They need to be able to see through us to God who motivates us. We are the "earthen vessels" that carry the treasure.
Because our fight is spiritual, Satan uses subtlety in deceiving us. Satan tempts good people to do good things, instead of doing the right thing, so that we start out moving in the spirit and end up moving 'in the flesh'. (Gal 3:3) The knowledge and practice of discernment of spirits* is very important at this level.
In dealing with the world we need to think with "the cunning of the serpent" and act with "the simplicity of the dove". For us to resort to deception would be counter-productive because bringing Humanity home to God requires a free choice based on truth.
* See attachment below for a summary of Catholic teaching on discernment of spirits.