Catholic Priests Not Able to Marry: Why can't Catholic priests marry? [I Timothy 3, Titus 1]. Divorce & Remarriage: Is it an unforgivable sin to get divorced or remarry? [I Corinthians 7, I Corinthians 6:9-10, Galatians 5:19-21]. Remarriage After a Groundless Divorce: What if there were no legitimate grounds for divorce and someone has already remarried?