If you search this site using the terms "church carry" you will get about 88 pages of posts dealing with this in one form or another.
You can look up any Texas statute here: http://www.statutes.legis.state.tx.us/" onclick="window.open(this.href);return false;
although not all the changes from the last legislature have been incorporated on line yet.
The part you are looking for is in the Penal Code, section 46. To swipe Mr. Cotton's summary from another post (with my emphasis):
TPC §46.035(b)(4)-(6) makes it unlawful for an armed CHL to go on the premises of a hospital, nursing home, amusement park (as defined) or church.
TPC §46.035(c) makes it unlawful for an armed CHL to go on the premises of a meeting of a governmental entity.
However, TPC §46.035(i) adds another element to the offense by stating that the above-referenced locations are off-limits only if the CHL is given effective notice as required by TPC §30.06.