My question is that in philosophy there is a doctrine "pragmatism" which define that "truth that we know today might be changed tomorrow as future is clearly uncertain. We try to discover things in every branch of knowledge just to solve the problems of today but we can be wrong in future". As we know that this is the principle on science, philosophy and in fact all knowledge is based. Now we come to Islam. Again we try to prove and defend the concept of God and other concepts by using reason of worldly knowledge that we know. Then how are we certain about those concepts as there are reasons against those concepts? How do we believe in them as eternal and never reversible facts when every truth can be changed?
There are two types of truth and pragmatism relates to the second of these:
The first are called absolute truths like universal moral truths and established truths which do not change with change in time or circumstances or intellectual development as for example the oneness of God, honesty, justice etc.
The second are called relative truths in which one has to apply one's mind on data to come to a conclusion. This includes interpretation from holy texts and scientific theories. These truths can change when an "alternative" and "more convincing" truth comes up.
You can now see that the issue you have raised does not arise about the first type of truths.