162nd Pope of the Catholic Church. Pontificate 1119 - 1124. His pontificate was shaped by the Investiture Controversy, which he was able to settle through the Concordat of Worms (in 1122). Callixtus opened the First Council of the Lateran in 1123 which, among other things, passed several disciplinary decrees, such as those against simony and concubinage among the clergy. Decrees were also passed against violators of the Truce of God, church-robbers, and forgers of ecclesiastical documents.