There are multiple ways, all of which are useful for you to decide whether it's true or not.
First, you can trust in the wisdom of those who came before you, i.e. scripture. Second, you could trust in tradition, which may say such things. Third, you can use reason yourself. Fourth, you could rely on personal experience.
First, you can trust in the wisdom of those who came before you, i.e. scripture. Second, you could trust in tradition, which may say such things. Third, you can use reason yourself. Fourth, you could rely on personal experience.