Here's the statute in the Texas Penal Code about where CHL holders may carry and how they may be excluded from a property. Note that posting such a sign only keeps out the law-abiding citizens who will leave their guns in the car or won't enter. It will not keep out criminals who, by definition, do not obey the authority of the law and will therefore disregard such a sign. Criminals also are unlikely to even be eligible for a CHL which requires a stringent background check and clean criminal history among other things.
So CHL holders fall under this law:
Sec. 30.06. TRESPASS BY HOLDER OF LICENSE TO CARRY CONCEALED HANDGUN. (a) A license holder commits an offense if the license holder:
(1) carries a handgun under the authority of Subchapter H, Chapter 411, Government Code, on property of another without effective consent; and
(2) received notice that:
(A) entry on the property by a license holder with a concealed handgun was forbidden; or
(B) remaining on the property with a concealed handgun was forbidden and failed to depart.
(b) For purposes of this section, a person receives notice if the owner of the property or someone with apparent authority to act for the owner provides notice to the person by oral or written communication.
(c) In this section:
(1) "Entry" has the meaning assigned by Section 30.05(b).
(2) "License holder" has the meaning assigned by Section 46.035(f).
(3) "Written communication" means:
(A) a card or other document on which is written language identical to the following: "Pursuant to Section 30.06, Penal Code (trespass by holder of license to carry a concealed handgun), a person licensed under Subchapter H, Chapter 411, Government Code (concealed handgun law), may not enter this property with a concealed handgun"; or
(B) a sign posted on the property that:
(i) includes the language described by Paragraph (A) in both English and Spanish;
(ii) appears in contrasting colors with block letters at least one inch in height; and
(iii) is displayed in a conspicuous manner clearly visible to the public.
(d) An offense under this section is a Class A misdemeanor.
(e) It is an exception to the application of this section that the property on which the license holder carries a handgun is owned or leased by a governmental entity and is not a premises or other place on which the license holder is prohibited from carrying the handgun under Section 46.03 or 46.035.
Note that this law says there are places that a CHL holder may always or may never enter with his legally concealed handgun. Those places are listed in different statutes, which I'll post below.
The first statute that the 30.06 code mentions is 46.03. 46.03 applies to all people with weapons. It makes taking a weapon to certain places completely off limits. Note that churches are not included in that list, so it isn't relevant to your current situation.
Sec. 46.03. PLACES WEAPONS PROHIBITED. (a) A person commits an offense if the person intentionally, knowingly, or recklessly possesses or goes with a firearm, illegal knife, club, or prohibited weapon listed in Section 46.05(a):
(1) on the physical premises of a school or educational institution, any grounds or building on which an activity sponsored by a school or educational institution is being conducted, or a passenger transportation vehicle of a school or educational institution, whether the school or educational institution is public or private, unless pursuant to written regulations or written authorization of the institution;
(2) on the premises of a polling place on the day of an election or while early voting is in progress;
(3) on the premises of any government court or offices utilized by the court, unless pursuant to written regulations or written authorization of the court;
(4) on the premises of a racetrack;
(5) in or into a secured area of an airport; or
(6) within 1,000 feet of premises the location of which is designated by the Texas Department of Criminal Justice as a place of execution under Article 43.19, Code of Criminal Procedure, on a day that a sentence of death is set to be imposed on the designated premises and the person received notice that:
(A) going within 1,000 feet of the premises with a weapon listed under this subsection was prohibited; or
(B) possessing a weapon listed under this subsection within 1,000 feet of the premises was prohibited.
(b) It is a defense to prosecution under Subsections (a)(1)-(4) that the actor possessed a firearm while in the actual discharge of his official duties as a member of the armed forces or national guard or a guard employed by a penal institution, or an officer of the court.
The second code mentioned in 30.06 was 46.035. This one gets people confused. It says where CHL holders (as opposed to other groups of people, which are dealt with in yet another section which I'll post below) may or may not go. So we're again dealing now with the law-abiding crowd. It looks at first glance like it says churches are always off limits, along with amusement parks and hospitals, etc. That was the intent and actuality when that law was first passed. Then they came back and amended the law, which you can see at the bottom line of it. They added the text saying those three places (hospitals, amusement parks, and houses of worship) have to give effective notice under 30.06 (have to post a valid sign, give written notice, or give verbal notice as 30.06 insructs in order to keep out the law abiding CHL holders), which means hospitals, churches, and amusement parks are just the same as any other random place now and are not in a special category. CHL holders may carry there unless given valid notice otherwise.
PC ยง46.035. UNLAWFUL CARRYING OF HANDGUN BY LICENSE HOLDER.
(a) A license holder commits an offense if the license holder carries a handgun on or about the license holder's person under the authority of Subchapter H, Chapter 411, Government Code, and intentionally fails to conceal the handgun.
(b) A license holder commits an offense if the license holder intentionally, knowingly, or recklessly carries a handgun under the authority of Subchapter H, Chapter 411, Government Code, regardless of whether the handgun is concealed, on or about the license holder's person:
(1) on the premises of a business that has a permit or license issued under Chapter 25, 28, 32, 69, or 74, Alcoholic Beverage Code, if the business derives 51 percent or more of its income from the sale or service of alcoholic beverages for on-premises consumption, as determined by the Texas Alcoholic Beverage Commission under Section 104.06, Alcoholic Beverage Code;
(2) on the premises where a high school, collegiate, or professional sporting event or interscholastic event is taking place, unless the license holder is a participant in the event and a handgun is used in the event;
(3) on the premises of a correctional facility;
(4) on the premises of a hospital licensed under Chapter 241, Health and Safety Code, or on the premises of a nursing home licensed under Chapter 242, Health and Safety Code, unless the license holder has written authorization of the hospital or nursing home administration, as appropriate;
(5) in an amusement park; or
(6) on the premises of a church, synagogue, or other established place of religious worship.
(c) A license holder commits an offense if the license holder intentionally, knowingly, or recklessly carries a handgun under the authority of Subchapter H, Chapter 411, Government Code, regardless of whether the handgun is concealed, at any meeting of a governmental entity.
(d) A license holder commits an offense if, while intoxicated, the license holder carries a handgun under the authority of Subchapter H, Chapter 411, Government Code, regardless of whether the handgun is concealed.
(e) A license holder who is licensed as a security officer under the Private Investigators and Private Security Agencies Act (Article 4413(29bb), Vernon's Texas Civil Statutes) and employed as a security officer commits an offense if, while in the course and scope of the security officer's employment, the security officer violates a provision of Subchapter H, Chapter 411, Government Code.
(f) In this section:
(1) "Amusement park" means a permanent indoor or outdoor facility or park where amusement rides are available for use by the public that is located in a county with a population of more than one million, encompasses at least 75 acres in surface area, is enclosed with access only through controlled entries, is open for operation more than 120 days in each calendar year, and has security guards on the premises at all times. The term does not include any public or private driveway, street, sidewalk or walkway, parking lot, parking garage, or other parking area.
(2) "License holder" means a person licensed to carry a handgun under Subchapter H, Chapter 411, Government Code.
(3) "Premises" means a building or a portion of a building. The term does not include any public or private driveway, street, sidewalk or walkway, parking lot, parking garage, or other parking area.
(g) An offense under Subsection (a), (b), (c), (d), or (e) is a Class A misdemeanor, unless the offense is committed under Subsection (b)(1) or (b)(3), in which event the offense is a felony of the third degree.
(h) It is a defense to prosecution under Subsection (a) that the actor, at the time of the commission of the offense, displayed the handgun under circumstances in which the actor would have been justified in the use of deadly force under Chapter 9.
(i) Subsections (b)(4), (b)(5), (b)(6), and (c) do not apply if the actor was not given effective notice under Section 30.06.
So what's to keep some random guy from taking a firearm into a church office and shooting up the place? Well, in actuality, a written law will do nothing to
prevent it. However, 46.02 is the law that makes it illegal. It prevents criminals, riff-raff, random guys, and any others who do not have a CHL from entering a church or other property with a firearm. But you and I both know that this law written on the books isn't going to stop someone intent on walking into a church office and killing the pastor/rabbi/imam/priest from doing so, so what possibly can?
An armed officer in the church office at all times? Self-defense tactics available to the church personnel? The church personnel and parishioners including law-abiding citizens with concealed handgun licenses who can protect their own lives and those around them should a criminal threaten their lives? The last is not an option if the pastor/priest/imam/rabbi and his staff who underwent background checks, took 10-15 hours of classes minimum, passed a shooting test, and paid for the right to legally carry are forbidden from legally carrying concealed there because the church posted a valid 30.06 sign that kept them and their legally concealed firearms out, but did nothing to keep out the criminal with deadly intent.
Sec. 46.02. UNLAWFUL CARRYING WEAPONS. (a) A person commits an offense if the person intentionally, knowingly, or recklessly carries on or about his or her person a handgun, illegal knife, or club if the person is not:
(1) on the person's own premises or premises under the person's control; or
(2) inside of or directly en route to a motor vehicle that is owned by the person or under the person's control.
(a-1) A person commits an offense if the person intentionally, knowingly, or recklessly carries on or about his or her person a handgun in a motor vehicle that is owned by the person or under the person's control at any time in which:
(1) the handgun is in plain view; or
(2) the person is:
(A) engaged in criminal activity, other than a Class C misdemeanor that is a violation of a law or ordinance regulating traffic;
(B) prohibited by law from possessing a firearm; or
(C) a member of a criminal street gang, as defined by Section 71.01.
(a-2) For purposes of this section, "premises" includes real property and a recreational vehicle that is being used as living quarters, regardless of whether that use is temporary or permanent. In this subsection, "recreational vehicle" means a motor vehicle primarily designed as temporary living quarters or a vehicle that contains temporary living quarters and is designed to be towed by a motor vehicle. The term includes a travel trailer, camping trailer, truck camper, motor home, and horse trailer with living quarters.
(b) Except as provided by Subsection (c), an offense under this section is a Class A misdemeanor.
(c) An offense under this section is a felony of the third degree if the offense is committed on any premises licensed or issued a permit by this state for the sale of alcoholic beverages.