I Don’t Believe What I Don’t See

How can I believe in the existence of the unseen like angels, paradise and hell even though I can't see them?

Eye is a limited organ which can see a small number of objects, however world is not just what we see. To give a simple example, even though we can't see the infrared waves, they are always there.
People who believe in materialism assume that the existing world is only of matter. However, existence has degrees and the lowest degree of existence is the existence of “matter” which is the weakest and the mortal. Therefore, matter is exposed to decomposing, perishing, changing and vanishing. The only way to increase the degree of existence of matter is its wearing life and soul.
For instance, the essence of human is not body; it is “soul”, because without soul, body can’t see despite the eye; can’t hear despite the ear; can’t speak despite the tongue… When soul leaves the body through death, all abilities of body perish.
In this world, human is in a test of believing the “unseen”. We believe in God, the angels, paradise and hell even though we don’t see them, because seeing is not the only evidence of existence. Therefore we can’t deny just because we don’t see. There are many evidences of existence. For instance, mind and soul cannot be seen, however they have so many proofs that people never doubt their existence.
For detailed information about "proofs of the unseen", you can read related links;
Proofs of Angels

Proofs of Afterlife

Is it possible to Prove the Existence of God?