I mean certain knowledge. I am not confident we can have. We as humans tend to want to support our hopes. We look for facts which indicate that they may be true. I assume look for facts which support your hopes, and those of the Islam faith probably look for facts which support their beliefs.
Many scientists probably look for facts to bolster their beliefs and hopes.
The bigger a belief structure becomes the more resistant it becomes to being shaken and dislodged. The old testament seems to support a GOD which condones violence and deception. Also a GOD which is not omnipresent and all knowing. These are beliefs which Christianity supports, however not beliefs that are supported by the Old Testament. In addition the bible has many, many apparent contradictions.