Water stoop

Some background information here.

In the church at Rennes Le Chateau which is a theme found heavily in the LRB there is this phrase carved into a water stoop:

"Par ce Signe tu le vaincras"

The water stoop is perhaps one of the most famous items in the church, due to the crouching devil upon which the holy water stoop resets.

Above the stoop are four angles, each signalling to a section of the cross. The idea being that you touch the holy water and make the sign of the cross (which is a common ritual for Catholics entering a church).

Hence "by this sign you will conquer" and the implication being the devil that will be conquered. This phrase in Latin "hoc signo vinces" is of course tied in with Constantine's vision of the Chi Rho.

Yes, most definitely, and I forgot to include the fact "Terribilis Est Locus Iste" is written above the entrance door at the RLC church in that section.

Here is nice tie-in with the devil of the water stoup at the entrance, provided by Fulcanelli:

“It is thus that the ground plan for a Christian building reveals to us the qualities of the first matter, and its preparation by the sign of the cross, which points the way for the alchemist to obtain the First Stone- the corner stone of the philosophers’ Great Work. It is on this stone that Jesus built this Church; and the medieval freemasons have symbolically followed the divine example. But before being dressed to serve as a base for the work of Gothic art, as well as for the philosophical work of art, the rough, impure, gross and unpolished stone was often given the image of the devil.”

Thus the rough, unpolished stone of Freemasonry (Rough Ashlar) is the foundation for the work being described. The devil greats those at the entrance and thus also represents the candidate upon their own "arrival" (initiation); as a rough, unpolished stone.

Thanks. That is a very interesting interpretation!