What we suffer from to-day is humility in the wrong place. Modesty has moved from the organ of ambition. Modesty has settled upon the organ of conviction; where it was never meant to be. A man was meant to be doubtful about himself, but undoubting about the truth; this has been exactly reversed.When I say that the Bible is true and certain, I am not making a claim about myself or my ability to know, but about God's ability to reveal truth to us. I am claiming fallible knowledge of an infallible God.
The Bible is full of declarations that we can have knowledge of God, his character, actions and will for the world. Luke wrote his Gospel so that "you may know the certainty of those things in which you were instructed". Either the Bible is being ridiculously over-optimistic about our ability to know, or certainty isn't the infallible God's-eye-view that we sometimes assume.
Epistemological certainty as Sipech describes it is a mirage. We are finite creatures, so we can never have 100% certainty about anything, even that you're using a red laptop, or that you live on planet Earth, if you really stop to consider all possibilities. (I blame Descartes. If you start your epistemology by doubting everything, then in the end even "I think, therefore I am" becomes uncertain).
All knowledge begins with faith in something, whether that's individual reason, sense perception, majority opinion, divine revelation, or whatever. What makes that faith epistemologically justified is that it continues to make sense of the world better than other available starting points.
For the Christian, our epistemological starting point is that God has revealed himself to us. We might by comparison find another starting point that better explains the available data to us, but that will equally be from a position of faith. All human knowledge rests on both reason and faith, no matter how hard people try to suppress their faith - such as the New Atheists, with their naive view that they use rational thinking alone, unlike those faith-heads with their blind belief.
We must always be revising our understanding and reforming our interpretation as we read and reread the Bible under the guidance of the Holy Spirit. We must never confuse our interpretation with the reality.
But we shouldn't be taken in by the black-belt interpretive ninjas who creatively reinterpret parts of the Bible that don't fit with their systems. When someone tries to convince you the interpretive equivalent of black is white and up is down, the best thing to do is often to reread what the Bible actually says, and laugh. We often mistake our difficulty with accepting or obeying the Bible for uncertainty or lack of clarity in the Bible.
Some details in the Bible are unclear and uncertain, but the big picture is clear: God made the world, Jesus died on the Cross and rose again, God sent his Holy Spirit, and so on. We can know these things. The question is, what's your starting point for knowledge - where are you placing your faith?