One way we can express reasonable belief in God is using references outside of scripture to start. Most people who don’t believe won’t start off relying on scripture seeing that they don’t believe in God and won’t see reason with a book that was man-made.
I would express that it is reasonable to believe in God by reasoning cause to affect. I would start with the Cosmic Wonder stating that space, time, and matter had a beginning. Nothing cannot produce something. Everything must come from something that already existed. This means that there must be some unique being that exists without a cause, that did not spring out of nothing, that is its own cause and the source of everything else. That one being who is Being itself is God.
Another reasonable argument for belief in God is moral realism. We have moral feelings and obligations that we intuitively know. We know right from wrong because it has been written on our hearts. If there is no God, moral obligation appears to be an illusion caused by our evolutionary biology or culture. If there is no God, then whatever we do is just a matter of opinion (ex. Torturing babies for fun). If we have moral values and we do believe that some things are absolutely wrong to do, then it makes more sense in a universe created by a personal God to whom we feel responsible than it does an impersonal universe with no God.
I would also express the fine-tuning and design of the world. The fine-tuning of the Universe is due to either physical necessity, chance, or design. The characteristics of design in the Universe demonstrate the existence of a Designer. When we look at something like a watch, we know that it had to have a watchmaker. When we see a building, we know that it had to have a builder. Like that, when we see creation, we come to believe that creation must have a creator. Either you have to take a great step of faith to believe there is a God who designed the Universe, or you must take a great step of faith to believe that everything was designed on its own.