I'm a religious man, and while what I practice may be quite opposite of a lot of people, I don't think I ever thought that without belief in God there would be "no hope, despair, and misery," as you put it.
I have a lot of friends who are atheist, I love them dearly, and I don't know any who are without hope, who are in despair or miserable. They have different convictions, yes, but aren't any less happy as I can tell.
Now I am very glad you have found peace with your state in life. Don't get me wrong. I myself am at peace on the path I walk.
But I am not a theist because I felt having this belief would bring me hope or end despair and misery for me. I don't walk in the path I do because I thought it was a 'better alternative,' as if being an atheist is somehow worse on any level or in any respect. I am not now somehow gifted with greater hope and freed from misery because I hold that God exists. Hope is not the exclusive property of theists, nor is it an automatic virtue of belief in a higher being.
I know we all go through things in life that bring pain, misery, despair, and rob us of our hope. Granted, but atheists are no less incapable of such hope or freedom merely because they have a different view on the existence of deities.
If you truly believe in God, then do more than merely believe. Imitate God. God doesn't give life and breath only to believers. Belief is not a requisite for these things. With each heartbeat there is hope for another. With the end of one day there is always the hope of another and seeing the end of misery. If this is what God gives to all, as you believe, and God does it without a sermon or requiring one accept a certain creed, then being in God's image you must not see your neighbor on a path different than yours. Your neighbor is on the same one. Same world with you, same planet, same path.
Stars are faithful in following the courses mapped out by God for them to follow. They are more faithful than you or I could ever be. Yet they have no belief in God, and compared to us they live virtually forever, almost it seems. So do not judge the way others go down the path set for them by their Maker. They may be more faithful in following it than you, even if like the stars they have no belief in God.
Do not see your atheist neighbor as without hope or in despair or without a future. And do not mistake your belief in God as something that guarantees such things either. Instead be grateful for the hope and peace you have and share the comfort it brings you with others, without a sermon just as God gives us gifts. For if there is a God, and God is love, then you are likely to be surprised with eternity and who you will find sharing it with you.