See whether your teacher lives by the ethical standards that he preaches. A good teacher gives his students room to argue, and encourages them to develop their own critical abilities. They want to check if the students are mindlessly accepting whatever is being taught, or if they are listening with a critical ear. First of all, let's define our terms. Truth, facts or principles attained through investigation of evidence.
Faith is usually a product of desire.
It's so hard to turn one of these tips down because we all desire to make money quick. A lot of smart people who have better sense have gotten fleeced because they ignored the evidence and went with their feelings. Knowledge, meanwhile, is based on evidence. In other words, seeing is only one way of believing. There are many other ways to collect evidence and draw conclusions.