Believing is something that you do.
Faith is what you do it with.
Faith is a kind of personal power you have. You can put it in concepts and ideas in your head and make agreements with it. Or you can put your personal power of faith within your self.
A warrior refrains from the first, and does the latter.
Faith is a force you command. You have the power to put faith in something or someone. When you do we say that you believe in an idea or a person.
Confidence is the feeling you create for your self by investing your faith in something or someone. Oddly you can create this feeling of confidence even if the idea is a lie or the person you believe in is a fraud.
A spiritual warrior is aware of how his or her belief in something can create a false sense of safety.
Practices for spiritual warriors in Self Mastery