My understanding of the law is that you could have a loaded gun in a secured container while on the "schools"/churches property but could not carry unless you had a CHP and you didn't leave your car.
Since the property of the school is the same as the property of the church the "good & sufficient reason" to carry in the place of worship is trumped by the VA law forbidding carrying (outside your car for CHP, or secured in a container & not taken out while on property for everyone else) while on school property.
Without the CHP you couldn't carry within 1000 feet of school property because of the GFSZ (which I know many believe is unenforceable).
Unfortunately (and the bill that changed this got killed this year) the first offense is a felony.
§ 18.2-308.1. Possession of firearm, stun weapon, or other weapon on school property prohibited.
B. If any person possesses any firearm designed or intended to expel a projectile by action of an explosion of a combustible material while such person is upon (i) any public, private or religious elementary, middle or high school, including buildings and grounds; (ii) that portion of any property open to the public and then exclusively used for school-sponsored functions or extracurricular activities while such functions or activities are taking place; or (iii) any school bus owned or operated by any such school, he shall be guilty of a Class 6 felony; however, if the person possesses any firearm within a public, private or religious elementary, middle or high school building and intends to use, or attempts to use, such firearm, or displays such weapon in a threatening manner, such person shall be sentenced to a mandatory minimum term of imprisonment of five years to be served consecutively with any other sentence.