How much do you actually know about the Bible? It seems everyone thinks they know a lot about it, but usually, the ones who claim to know the most about it are those who have never read it.
A good question to ask is where your knowledge of the Bible comes from. Perhaps you're remembering what you were taught in Sunday School. Perhaps, you were taught select pieces of information in a high school Religious Studies class. The media, your friends, maybe you've even read books about the Bible. One of my greater fears as an internet preacher is that I might make an error, and one of my followers will not be wise enough to test it before they take it to other people, who also will not test it. But of course, this job is a dual effort. I make the effort to fact check my articles before I share them, but it's on you, the reader, to decide if I have done a good job.
This is vital for three reasons. For the believer, what you have been taught might not be correct. There could be countless doctrines to which you hold that the Bible either does not necessarily teach, or even that it teaches against. Just because you were raised with those doctrines does not make them irreproachable.
For the skeptic, it is possible that you were force fed Christianity as a child, and as such you have become opposed to it. We're all familiar with such people. If you don't know one, it's possible that you are one. But is the faith you were force fed the faith you are criticising? To this day, I have never met someone who says they were raised in the faith, yet apostatised, who actually understood it.
Even if you were not raised in the faith, but nevertheless criticise it, does it not make sense to study the faith you criticise? Put it this way, if you debate enough Christians, you are statistically certain to find one that doesn't know your own faith. So imagine, if indeed you need to imagine, if they criticised it based on their misunderstanding. Evolutionists, what if a Christian asked you why we still have monkeys? Muslims, what if a Christian said Islam is wrong because Muhammad said Jesus doesn't exist? Catholics, what if a Christian criticised you for saying Mary is a member of the Trinity? Whatever your current faith, imagine the most annoying straw man possible, then think how you feel when someone makes it.
You see, then, how understanding Christianity is vital for both practising it, and for criticising it. If you claim to be Christian, it is vital to study the Bible, because you will fail both in practising and sharing your faith if you do not. If you have always been sceptical, and seek to criticise Christianity, it is vital to understand it, lest you make an embarrassing rookie error, and even so that you can know if your criticisms are valid. If you were raised Christian, yet have rejected it, it is vital to understand the faith so you can know if your decision to leave was wise, and it is doubly embarrassing for you to make those rookie errors.
No matter who you are, your study of Christianity should go far beyond a casual Google search, or knowledge you have absorbed from your culture, or even what you have been taught by your Church, your family, and your school. Reading the Bible should be a continuous exercise. Even completing it once will not be enough. Read it twice, three times, four times, it will never run out of things to teach you.