In Pursuit of the Truth

What we believe to be true, is it really the truth? Do we just believe that it is true because we were taught that it is the truth and never looked any further? How do we really understand what the truth is? Is there any guidance or reliable sources which we can refer to, to know the reality? What is the purpose of our existence?
These are a few questions which come up in an inquisitive mind! Sadly, in this world which is filled with corruption, immorality, pride & wickedness, it is extremely hard to blindly trust any sources which pose to be true! This was the state of mind of people from time unmeasured till today!
However, testing every source, guidance & all sorts of means available, fortunately we can come to the conclusion of having a reliable source to begin our quest for truth - the Holy Scriptures! These were revealed to the humans as an answer to their quest for truth found in the entity called "God".