Religion:
1. beliefs and worship: people's beliefs and opinions concerning the existence, nature, and worship of a deity or deities, and divine involvement in the universe and human life
2. system: an institutionalized or personal system of beliefs and practices relating to the divine
3. personal beliefs or values: a set of strongly-held beliefs, values, and attitudes that somebody lives by
Cult: (now this is in my words, but I believe that others would basically agree)
A structured religion in which (1) members are required to pay money to be a member or progress within the religious structure, (2) members are segregated from their family or other outside influences as part of membership, (3) members are forbidden from leaving and harassed if they do manage to leave, or any combination of the above.
Most Christian religions do not require any money whatsoever (although they do encourage charity and giving). They often condemn other beliefs, but, especially in the case of the modern Catholic church, encourage study and exploration of other belief systems as a way for members to reaffirm their own beliefs. And if a member does decide to leave, other members often reach out to them, however the level of contact rarely ever (I sadly cannot say never) even approaches many of the things Scientology has done.