Truth and Falsity: Is the world too complex for us?

"What is Truth?". These were the words of Roman governor Pilate when dealing with the "Jesus Christ" case.
Through these words, we understand the question as: "Does a perfect understanding of the world exist?". These are typical questions of a deeply religious person who is already convinced that such a "Truth" exists.
For most other people, we are living in times of uncertainty where our strongest believes are put to the test day after day. If you open up your own dictionary, you would find such a definition for truth: "conformity with facts, agreement with reality". A "true" statement is opposed to a "false" statement. This is quite different from the opposition between "saying the truth" and "saying a lie - being insincere".
For example: "Thailand is north of Malaysia" is true. "Mexico is north of USA" is wrong.
"I am a Martian" is an insincere statement as I cannot honestly believe I am a Martian.
What really matters is the so-called "scientific" approach to determine what is "true" as opposed to what is "wrong".
Let us give another example:
In January 2003, the Bush administration declared that they had enough evidence to conclude that the Saddam Hussein regime had Weapons of Mass Destruction (WMDs). This statement is now known to be wrong. Does it mean the Bush administration was lying? They said they didn't lie but did an "honest mistake". In other words, they would have been misled by "faulty evidence".
Saying that someone said something wrong does not always mean he was a lier, it could also mean he didn't have enough solid evidence to find out properly about "the truth". (Wether the Bush administration was aware that their evidence was not perfect is another issue).

So far, things seem to be easy. Let us just adopt a scientific approach in all our casual and formal investigations, and we can all discover the truth about anything. Or is it so?