There are many things about which we can be sure. The sun will rise, the moon will set, the stars will shine. Science is often the basis of our certainties. It answers so many of our questions about the nature of the world.
When we doubt, it is because our faith is shaken. For those of us who are atheists, or that wishy-washy alternate belief system- agnostic, faith is not really on the table. At least not in the traditional way. We who are “non-believers” are still hopeful. Often that hope is based on so little in reality as to almost mimic religion.
Having hope is not antithetical to agnosticism or atheism. It is a state of happy anticipation. Doubt throws us into a dystopian state of mind.