The Muslims will tell you to repeat the name of Allah until you come to believe. The Christians will tell you to open your heart to Jesus to find true belief. These are easy answers that bend you in the direction of your initial starting point. This isn’t the case with reason. When you form beliefs on the basis of evidence, no conclusion will be guaranteed. Everything will be up for grabs. There’s no book that can teach you how to do this; it is not just a skill set, it is an attitude. So, my suggestions: Be genuine and sincere with yourself and with others.