I am not a Christian, but I force myself to believe in God because I fear Judgment. I always shiver and cry because I don't know if I will go to hell or heaven. My fear is so strong that I became depressed and desperate for few weeks. My grandfather is Buddhist but told me that he is more agnostic and told me that God is just an example for humans to follow, not a real being who guides us. I didn't know what to believe and also I don't know how should I feel about God (if He exists). I am afraid of God, so much that I don't see a God who is going to forgive me, but a God who will throw me to hell.
I've puzzled over your note for a while because there is contradictory information being given and I wondered how to best approach your question.
As a Christian, I agree that you and everyone else should fear God. "And do not fear those who kill the body but cannot kill the soul. But rather fear Him who is able to destroy both soul and body in hell" (Matthew 10:28). The fact that you have fear of God and His Judgment tells me that on some level you understand and believe that God exists, that He created this world, and that we are accountable to Him. "Let us hear the conclusion of the whole matter: Fear God and keep His commandments, for this is man's all. For God will bring every work into judgment, including every secret thing, whether good or evil" (Ecclesiastes 12:13-14).
Fear ought to then become a motivator to check to see if your fear is justified or not. "The fear of the LORD is the beginning of knowledge, but fools despise wisdom and instruction" (Proverbs 1:7). However, it appears you have met your fear by locking up. You express doubt but you haven't yet investigated.
Your grandfather appears to see God as a concept, which is very much a Buddhist way of thinking. Concepts are vague. They don't demand changes in a person's life. There is no accountability for individual actions to a concept. But then, concepts are individualistic. In reality, your grandfather's idea of God is only of his own imagination. "O LORD, I know the way of man is not in himself; It is not in man who walks to direct his own steps" (Jeremiah 10:23). The result is that there is no higher being that your grandfather believes is over him. Yet, such a belief doesn't match the world. How did this world come into being with so many parts interacting and dependent on each other without a higher designer and creator? Individual concepts don't create universes.
What I would suggest is that you investigate whether it makes sense that God exists and whether that Creator has a plan for His creation. If you would like to study this with me, I would be happy to do so.