Thank you for your question. Faith is a personal matter in the sense that faith is to do with the individual. God has guided humans as to how to develop that faith correctly though revelation to some of His exceptional servants. However, religion is wider than the individual and at the same time affects an individual's faith. Religion is concerned with how humans live together as well as how they are as individuals. A belief system is formalised since the scriptural sources are at times inaccessible to lay believers and organisation is part of creating a society of believers.
May you always be successful