Lies are a dangerous sin to commit because they threaten and distort perceived reality. To tell a lie and be believed is to convince the believer that what is real is unreal, or that the unreal is real. While a lie may never be found out, any unreal event housed within the real necessarily calls attention to itself by having no referent.
The best way to avoid being caught in a lie is to have nothing to lie about. The best way to keep a secret is to have no secrets to keep – alternatively, never, ever tell anyone.
Because of the natural chain of events that is cause and effect (that same chain which necessitates that all events be the same infinite event), any false or unreal event introduced into that chain is easily traced backward to its source – the liar. A thorough, deductive investigation of the chain of events which led to the unreal event, will inevitably uncover the liar because the unreal event seems to have an inappropriate cause or no cause at all. In order to conceal a lie well, one must then concoct further lies which support it, masking the flaws in the chain of events.
Naturally, the more lies one tells, the more unlikely that the chain of real events will cohere with the lie, and then it will be discovered. However, some will not delve as deeply into the chain as others, leaving the lie to persist.
As such, there are cases where a lie cannot be easily discovered by deductive reasoning, and the person who believes it will continue to live as though the lie were true. This is dangerous, because it introduces a false or unreal event into the chain of future real events, such that the unreal event becomes a factor in determining what will be real in the future.
This is all not to mention the emotional effects of a lie. For the liar - if the liar is not a sociopath - there will nearly always be pangs of guilt for having told the lie, which may or may not be bearable. There is guilt for having lied, and further guilt for having done or been involved with whatever thing caused the lie. Even in cases where no guilt is felt, it is highly likely that the liar will experience paranoia with regard to being found out.
For the person lied to, there is more often than not suspicion, and in such cases suspicion is sufficient cause for feelings of betrayal, regardless of whether those suspicions have been validated. If the lie is discovered, the feelings of betrayal and suspicion are validated, turning to anger, disappointment, and depression. This is before whatever truth that the lie replaced is discovered, and in some cases, the discover of the truth will cause further anguish.
As it is rarely advantageous to be the receptor of negative emotions (least of all, one’s own), it is rarely advantageous to lie. As stated, the lie is almost inevitably discovered, making the negative response and effects of altering the chain of events just as inevitable. In this sense, lies are in almost every case as much a self-destructive behaviour as they are an outwardly destructive behaviour.
Furthermore, the act of lying in conjunction with the true event which seemed to require the lie has an additive effect, which results in more negative response than would originally have been encountered were the event alone discovered. To an extent, this relationship mirrors western karmic theory, because in lying, negativity is visited back on the liar two-fold.