The Bible is God's Book of Rules for building Christian character, and also the Manual to decribe in detail the only way to get to Heaven. This is a starting point for faith. Take it for granted there is a God, and then act on what His Word declares. You could go to an eternity without God, if you take the risk, and do nothing. On the other hand, if you take it for granted there is a God you are well on the way to receiving the message in the Bible to show you how to get to Heaven when you eventually die.
Every building needs a reliable foundation.
Then it must be built with the aid of a ruler and level, for accurate measurements. Your dream house would be crooked and unlivable if you built by a changing set of rules. On this basis you can trust the jet to overcome the laws of gravitation, because another law comes in to supercede the first law. God's laws in all aspects of life do not change, other wise we would live in a constant state of confusion. So it is with the Bible as well.