“I'm afraid it is not open to the unenlightened. Your presence would contaminate our great works. However, if you are willing to be baptized in Atom's holy Light, then perhaps I could allow you to enter and meet our leader.”— Brother Gerard
Holy Light Monastery is a small settlement which is inhabited by the Apostles of the Holy Light. It has only one interior section.
Brother Gerard guards the entrance to a collapsed wooden building. Behind him there are two radiation traps which can be activated with a button on a stand nearby. In the corner of the building is a cellar door which leads to the "Eternal Light Monastery".
The "Eternal Light Monastery" features a small chapel with some benches where Mother Curie III preaches to a group of ghouls, with a book shelf off to the side of it. There are three beds for the cult followers, further downstairs are some radiation traps, a fridge, a table, a radio, two boxes of holy water and two non-hostile feral ghouls, called Atom's Champion and Sun of Atom (which can also go upstairs but are most often encountered downstairs).
The monastery (and the house above) contains radiation traps (four altogether), as the name implies they 'trap' and concentrate radiation by capturing local particles in a field. However, these traps cannot be triggered by anything other than intentionally activating them. The traps are useful to increase radiation level in order to get inside the monastery. These traps can be disabled.
If the monastery is visited before finishing Take it Back!, the building will look the same as it did without the add-on, albeit with an inaccessible cellar door.
There is an empty suitcase to the left of the front entrance to the monastery. However, it is not labeled as empty no matter how many times it is opened and closed.