words [dabar] of his mouth [peh] are
iniquity ['aven] and deceit [mirmah]: he hath left off [chadal]
to be wise [sakal], and to do good [yatab]. KJV-Interlinear
3 The words
of his mouth are trouble and deceit; he has ceased to act wisely and do good. ESV
The wicked, or those who lack the correct function of truth in their soul, center their lives on a false basis.
Their mouths express what is in their soul, and what is in their soul is false, therefore their words are false, regardless of what they might be.
The deceit, is a further expression of a wicked person who not only has false intentions in their soul, but go even further to falsify their intentions. Thus they compound the false onto the false. That makes deceit.
Now truth comes in many forms. Truth is the correct matching of facts with reality. Math is a form of truth. Chemistry is a form of truth. These things have the science of relationships and function within the universe.
Do not get the idea that truth is only limited to the words in scripture. Remember that God designed and invented and created all that is in this universe, including life, and the many things that we probably do not ascribe to God, but were His invention.
If science took a closer look at God, then they might discover many more things, even faster. God is logical and created this universe with a design and a plan. Thus everything has a purpose and function. Whether those things are the sub-conscious or sub-atomic particles, makes no difference. God designed it all.
So, truth saturates life in one form or another, but where people go wrong is when they make false or wrong applications or interpretations of truth. Then their conclusions or opinions are wrong and therefore false.
And, when your soul consists of the false, then morals sooner or later get twisted. And that is when people get hurt.
Beliefs become opinion, become bias, become immoral, criminal, subjective, etc. Wisdom and good, then take the back seat, while evil assumes the primary role of life.
Responsibility, obligations, integrity and such become compromised with whatever is convenient or advantageous to ones beliefs. And of course the pit gets even worse, as a person maintains this pattern of disregard for truth.
And truth? It does not function correctly, unless one is saved, in fellowship, and learning scripture as God intends for us to learn, and grow, and advance in our life.
The spiritual life ties all of the loose ends of life together, brings orientation and understanding to every aspect of life. And while we are not all rocket scientists, we do not have to be in order to understand life and God and doctrine, and our meaning and purpose and destiny.