One of the things Christians need to be prepared to do is to reasonably and rationally explain and defend the reasons for their faith. It is not enough to say, "The Bible says it and I believe it" to someone who rejects the Bible as nothing more than an interesting piece of literature, not the inerrant Word of God. What if you are speaking to an atheist, openly hostile to everything you believe? Will you be able to make reasoned arguments for your faith? What if you are accused of being "close minded" because you believe the only way to salvation is through Jesus Christ?
There are many apologetics resources available on the web. One of the ones I think is really helpful is Stand to Reason, a site which equips Christians to go into the world ready to defend their faith. Greg Koukl is the primary voice of Stand to Reason. The site has podcasts, blogs and different resources, free or for purchase. The resource I read always read is Solid Ground, a bimonthly newsletter which discusses current topics and gives tips on argument tactics. Greg Koukl has also written a book called Tactics which discusses how to control a discussion, like using the "Columbo tactic" or finding the flaws in other people's arguments like "Suicide" statements-a statement which contradicts itself. "There are no absolutes!" is a suicide statement. One cannot absolutely state there are no absolutes without violating that same statement.
Stand to Reason has great resources to expand your critical thinking skills. I hope you take advantage of it.