how could we believe in any religion? Since no one has able to see God, and since no dead person was resurrected to tell us what happened to him after death, how could we believe in any religion?

This question is based on the material world, where sense becomes the reference to determine the facts of the universe. Fundamentally, this basis is a void one. In this life we believe in many things without being able to see them or feel them tangibly. We do not know for example the essence of the soul, its secrets, and where does it inhabit our bodies? So far this field has been immune to scientists and scientific laboratories, fine radiology and microscopes, which biologists See More and doctors use. We absolutely believe in the presence of the soul although we do not see it. We also believe in the existence of many other things like magnetism, electric current, air and many other things, which we do not touch physically.
All religions are based on miracles, which God performs on the hands of the prophets. Ordinary human beings cannot perform these miracles. Only prophets could carry out these actions in order to confirm the fact that they are true emissaries of God. All prophets were sent to people and performed miracles in front of them, so that they believed them. These are well-known historical facts.
Prophet Moses (pbuh) performed miracles: his club was transformed into a snake, the sea was split into two parts through a hit with his club, and the bursting of the water from the rock in the form of twelve springs good for drinking.
Prophet Jesus (pbuh) healed the blind and the leprous, and gave life to the dead through God’s will.
Prophet Muhammad also had many miracles including the splitting apart of the moon, the gushing of water from his hands and the night journey from Mecca to Jerusalem and his ascension though the heaven. But the most enduring and challenging miracle revealed through him is the Qur’an.

The entire concept of faith is believing in something with no solid proof. Religion revolves around faith in God, despite the fact no one alive has seen him. Unless you count people who have had near-death experience (like if they have a heart attack and later come back due to CPR or resuscitation) - they sometimes tell of seeing dead relatives, which proves there is life after death through God, and others even say they have seen God himself. Resurrection is the theory of when See More the world ends, we come back to life through God, so logically this hasn't happened yet. But who's to say it won't in the future? The only person who the Christian bible says has risen from the dead is Jesus himself (and Lazarus, but Jesus did that, but technically Jesus and God are the same person through the trinity? Who knows?)

Apologies for the religious rant, but taking RE for my high school exams really has imprinted this into my brain

When your at your lowest is when we notice that God is there

You kinda just feel when God's there (but not all the time which is weird cos he's there all the time) it's like when someone really important walks in a room, you can tell. Hard to explain :(

well, if you want to go by what few people say, that they have died and gone to heaven and seen their dead relatives, then that is how, or you can see the logical parts in religious books! there is a movie coming out that is based of a true story about a kid who died for about a minute,, and was brought back to life, and he said e had seen his fathers father, and he wasn't the old guy he was when he died, but a young man in his prime, you have to see the movie for a better explanation.