1) Article of faith 2) Conviction 3) Strong belief 
• (n.) The practice, habit, or work of an amateur.
Am'a·teur·ism noun The practice, habit, or work of an amateur. 
[n] - the conviction that people should participate in sports as a hobby (for the fun of it) rather than for money
noun the conviction that people should participate in sports as a hobby (for the fun of it) rather than for money
the practice, quality, or character of an amateur or amateurish performance.