To believe in the Quran you have to believe in the unseen issues mention in the Quran.
In our time, human becomes more aware of what he does not know, or what he could not see while it is exists for real. Electricity is exists but we can not see it although we use it. Fire is unknown to us; we do not know its source or where its whereabouts. The same you can say about light, magnetism, gravity and the life itself. Going beyond these things is totally unknown to us. Allah, The Almighty God, know what he has owned and created (67 : 14 ).
In His Book , The Holy Quran. Allah mentioned some indications about these unknown scientific facts. We discover some of them in our recent time but there are some awaiting the coming generations.
However, it is up to any one to believe or not to believe in the Quran. ( 17 : 107)