Some people, when told that what they believe they can achieve, will point out that insane people may believe they are Abraham Lincoln, George Washington, or Jesus, but they don't actually become that person.  In a sense, they have a point.  We cannot become somebody else, but we can imitate the success of somebody else, whether it is business success, artistic success, or spiritual success.  We have to be realistic to some extent, for example, a seventy year old with severe arthritis isn't going to become an Olympic marathon winner, but many people become surprised at what they achieve when they ignore limitations that they think they have.  
    Some think they can't accomplish anything because they don't have a college degree.  Thomas Edison didn't have one and neither does Bill Gates.  
    Some think they can't become spiritual because they don't come from a very religious family.  St. Francis father was not a religious man and ho opposed Francis when he decided to become a monk.   Actually, some of the most spiritual people around today are former agnostics because the lack of a strong belief in the restrictive dogma of a major church allows them to explore the more open, creative and spiritual side of religion.
    So don't let the beliefs of others prevent you from developing spiritually, or otherwise.  Believe in yourself.