Creates the Faith Behind Bars Act. Provides that a person committed to a correctional institution or facility has a constitutional right to practice his or her faith in the correctional institution or facility absent harm and without undue burden to the State's correctional system. Provides that a committed person belonging to a faith group in a correctional institution or facility shall have access to pastoral and spiritual care absent harm and without undue burden to the State's correctional system. Provides that a correctional institution or facility shall provide reading materials for diverse faith groups, including, but not limited to, spiritual, religious texts, prayer manuals, prayer mats, and other requested material from committed persons. Provides that all correctional institutions and facilities in the State shall provide committed persons the ability to pray by facilitating time and clean location, fast by allowing a committed person to abstain from food when appropriate, and respect for dietary restrictions absent harm and without undue burden to the State's correctional system. Amends the Unified Code of Corrections to make a conforming change. House Floor Amendment No. 1 Replaces everything after the enacting clause. Reinserts the provisions of the introduced bill. In the Faith Behind Bars Act, changes definitions of "chaplaincy services" and "undue burden". Provides that a committed person has a right (rather than a constitutional right) to practice his or her faith group in a correctional institution or facility absent or without undue burden to the State's correctional system. Provides that absent harm or undue burden a correctional institution or facility shall provide reading materials for diverse faith groups. Provides in determining whether an action would result in an undue burden, warden or chief administrative officer of the correctional institution or facility shall consider security requirements that are necessary.