The scientist says “This is a fact I know” and “This is my interpretation of what it means.” The first part is always good. The second part is where scientists get in trouble.
The religious scholar says “This is what the Bible says” and “This is my interpretation of it”. The first part is always good. The second part is where religious scholars get in trouble.
Notice that the first part of each statement does not involve human judgement, and the second part of each statement does. We, as humans, get in trouble when we extrapolate from what we think we know. We all, me included, are guilty of this fallacy, and it applies to either field.
All fields of study suffer from this. How do you know if the interpretation is correct? What tests can you apply to improve your probability of acquiring the truth?
One test would be consensus. Do the majority of scholars in a field come to the same conclusions? This test is a strong indicator, but there is no guarantee that the majority are right; for instance, for hundreds of years the Catholic Church held that the Earth was the center of the universe, incorrectly. So while consensus is a strong indicator, one must always bear in mind the possibility of error.
Another test could be whether the subject agrees with your knowledge gained by experience. Do the conclusions of the scientist or religious scholar disagree with things you already know to be fact? If you KNOW that water runs downhill, and someone says it doesn’t (in ordinary circumstances), then they must be wrong. However, you do have to be very careful that what you think you know isn’t actually just an opinion of yours.
Is it possible to achieve 100% certainty? Well, frankly, no. Not in a world with humans in it. You may have a source of knowledge (i.e. the Bible, or well-established scientific knowledge), but the interpretation of that source is always going to be suspect to some degree. So if we are sane, we always swim in a sea of some uncertainty.
Absolute certainty, in a human, is only possible at a very basic level. For instance, I know for sure that I don’t have any shoes on right now. But if you are talking about anything at all that relies on human interpretation, you can only reasonably talk about probabilities.
Faith is a whole different kettle of fish. A person with faith will often equate it with certainty. But the wonderful thing about faith is that you, personally, act as if it were certainty even though you know nothing is 100% certain! That is why faith is the miracle that God demands of us – because it’s hard, in the beginning, to have faith, but very rewarding.
God wants us to choose to be His children. He wants us to have that choice to make. This requirement for an element of choice is why God has constructed a universe in which it is possible to not choose Him. If God had made His presence imminently obvious without ambiguity, like gravity, for instance, then no sane person could choose otherwise. So he created this universe in such a way that we have to choose Him by faith, not facts.
Once you’ve chosen Him, a lifetime of experience conspires to provide certainty, as experience piles upon experience to confirm your decision, and faith becomes easier. In your mind, you are certain – but you can never prove it empirically. Exactly as God wants it.