Hopes, can be either selfish (natural) or God-given (supernatural). God-given hopes are being able to see another reality - or having God's reality or plan for a certain thing revealed.
Faithful characters in the old testament were seen to be the ones who gave up their natural hopes for God-given ones.
The certainty of these hopes does not come from a mathematical or logical understanding of how these hopes will play out. Rather, the certainty is the realisation of these ideas through actions. Instead of separating off theory and practice (a la the Greeks) certainty of faith is putting theory into practice.
How can we practically do this? As faith is a gift, the first thing is to ask for it, and asking for it really means giving up your own selfish hopes. "Not my will but yours". It is a surrendering of our entire will - not just giving God a limited number of options, but being open to His.
Once this hope, or vision of God's reality is received, (through listening carefully, i.e. open to ideas etc from outside of our reality) something needs to be done as a demonstration of your certainty of that hope. Tell a friend, make a first step. Or as Pitt said to Wilburforce, "Quick, while we are still young enough to not understand that it is impossible."
