One builds faith through experiencing the teachings. We can experience causality in the everyday things we do. We get upset with someone and we feel badly. Either because we hurt the other person or simply because our outburst disrupts any peaceful thoughts we were feeling. When we help someone, the result is we feel better. When we chant, the result is that we feel calmer.
When we read the teachings they will make sense and explain things that were unexplained before. With more learning and experience from observing that they do work, we will develop our confidence. With practice we will experience the benefits. Gradually, when some number of the things that we can prove for ourselves are proved; we take the rest on faith. So we should not push ourselves to deepen our confidence; rather, we need to let it deepen as we see the truth and practicality in the teachings.