As you read this, a couple of things to keep in mind. I have worked in both personal security (bodyguard) and also in site security (facilities, I.E. buildings, warehouses, etc). I would not call myself an expert in the field, but I would claim experience in the field. These are some thoughts and observations based upon my experiences and work history. Take them as you will.
To start and to be blunt, if someone is bound and determined to kill people, it is important to recognize that they will probably succeed. I am not saying this to be cruel, I am saying this because when thinking about these matters, it is vitally important to understand the realities that surround them. What you hope for in security is two things really. First, you hope that you can deter “casual problems” if you will. This basically involves not being an easy target. Second, you are trying to minimize the damage to people and property should something happen. FEMA has a guide to developing emergency operations that I am told by people that I trust is useful. You can find it here:
Some insurance carriers also have useful suggestions and resources that a church can avail themselves of. Consulting with them is a good step. There are also firms that deal with risk assessment. There are books and other resources so that you can do it yourself as well. Those procedures will give you a good idea of where you stand.
So, the most obvious thing that you can do is have a working alarm system. Make sure it is known to be there. I suggest window stickers and the like. It is a bit tacky, but visibility of security is one of the best deterrents there is. The second most obvious thing that you can do is have a well lit lot and to also make sure the entrances are well lit. It sounds silly, but light is an enormous deterrent to criminal activity as well.
Some churches have gone the route of metal detectors and such. There are areas where that may be useful and necessary, but if you are not in a high gun crime area, it is most likely an annoyance and only deters your congregation. Some churches have weapon checks (primarily those providing ministry in heavy gang areas, etc.) that they use to find weaponry people may try to bring in. They often combine that with a weapon check (think coat check) to keep the service peaceful while still doing all they can to be welcoming. Such churches are often neutral turf for gangs and provide a forum for discussion with the goal of eliminating violence in their communities.
Some churches allow guns in their buildings where it is legal. Aside from whatever spiritual issues a person may have with this, there is a reason why guns are often disallowed in crowded public areas. There is a difference between a good shot at the range and a good shot when innocents are panicked and running around. The same goes for those churches who use armed ushers. If you are going to have an armed presence at your place of worship, please make sure it is a trained and reputable professional. As a general rule, I do not recommend this however. Not because I am against guns, but because there should be a difference between a house of worship and the security measures it takes, and the high end department store and the roaming armed guard there. Unarmed security is an option that provides a visible presence but does not provide a lethal response. Should you decide this route, I would strongly suggest a reputable local company. These companies are usually staffed by people from your general community so they are familiar with what they should look for etc.
The local police are a good resource. Most departments are willing to consult with businesses and charitable organizations about things to look for etc. Along those lines, I suggest a wireless panic button system for your church. Many school systems are starting to adopt these for use should there be an emergency. They increase response time of the police to you and that can only be seen as a good thing. I also suggest cameras at your entrances that record who is coming in and going out. This allows primarily for identification after something happens, but also serves as a visible deterrent.
Churches often bring in a fairly large amount of money in offerings on a Sunday. They are also often terrible at managing it. I suggest that all churches keep very little cash on hand at any given time. Get a night deposit key and use the bank’s night box Sunday after church. The number of churches who keep the money from the plate hanging around until Tuesday or Wednesday is staggering.
Finally, make sure that your staff and key volunteers are trained in what to pay attention to. Most criminal activity has certain tells that give it, or the potential for it, away. Seeing something that may be suspicious does not mean that you should over react (that is part of training) but that you should react proportionately.
Again, if someone is bound and determined to kill another, break into a place, etc. they are probably going to do it. Effective security prevents crimes of opportunity and effective planning allows for quick responses limited the risk and damage to people and property after an event occurs. I suggest that any of you involved with a church, encourage the appropriate board to review security measures and decide what is the most reasonable for your congregation.