We have some really interesting options in what to believe in in life.
If we would like the approval of a traditional community, we can simply adopt their beliefs. Most people do.
If we are concerned with believing what is True, rather than what is False, we could look to Religion. Many religions concern themselves with issues of what is True and what is False. Let's call these the True Religions, e.g., most versions of Christianity and Islam. The True Religions assert that holding the right beliefs is terribly important! And they tell us what those right beliefs are. Isn't it interesting that different True Religions disagree on these terribly important matters?
Some religions are designed to free us from our need to have rigid beliefs. Let's call these the Maybe Religions. The classic examples of Maybe Religions are Zen Buddism and Taoism. Are Buddism and Taoism religions? Maybe! Some versions of Christianity and Islam are also Maybe Religions - we'll have to look a bit to find them.
Many people in the modern world look to Science to find out what to believe. School science teachers and popular experts on Science will tell us what to believe. This is quite odd, as science does not deal in beliefs! The Scientific method is concerned with constructing and testing models of reality, and makes no claim about the actual nature of reality, if there is such a thing as reality and if it has an actual nature.
Mathematics provides a pretty firm foundation for belief. Mathematical methods exist which can often be used to prove statements true or false beyond a shadow of a doubt. What's the catch? The statements have to be mathematical claims about mathematical objects. Mathematics does not apply to the real world. Fortunately for Science, Mathematics applies quite nicely to Scientific Models. We have some clues about mathematics