Posts, church/large areas, building materials...
Let me 1st start by saying I did not read all the topic messages posted by will add my input;
Depending on a few important factors like $$$/budget, skill levels-training, the overall layout & construction of the church/related property, size of the crowds etc, I'd suggest the following;
The security detail members should be armed with either the HK P2000 LEM in .357sig or .40S&W, the Beretta PX4 C model in .40S&W, the Smith and Wesson M&P in .357sig or .40S&W(with the ambi safety), the SIG Sauer P226R or P229R DAK format in .357sig or .40, the Ruger SR40 .40S&W(if budgets are a major problem).
All the sidearms should have 3 dot night sights.
If any of the armed staff are in uniform or carry in the open, ambi-safety type models should be selected but overall, a DA only pistol(DAK, LEM or C type) should be issued. DA only pistols are safe & you avoid false claims of reckless or improper conduct(panic, cocking hammers, etc).
I'd suggest the armed church staff use a Safariland SFS or Blackhawk SERPA type security holster for weapon retention/officer safety. I also advise to use frangible or pre-fragmented rounds in .357sig or .40S&W from Glaser Safety Slug or Magsafe. ExtremeShock USA is on the US market but the quality is very low, in my opinion. The Hornady Critical Defense or TAP rounds may work too.
Special purpose or frangible loads are not cheap but may be a smart choice based on the building material(wood, marble, glass, etc) and large groups of church members. These rounds are designed to avoid over-travel, riccochets, etc. New designs feed well in quality semi auto pistols and function ok.
White lights & lasergrips are a good option but may be best for night use or low light conditions.
In closing I'd suggest using the .357sig first & if not practical, the .40 or larger .45acp.
Special purpose or frang