Here's a quote from a Christianity Today article about the mass shootings at the First Baptist Church of Sutherland Springs in Texas "The time has past for naivety about the need for security" AMEN - every church in America needs to be addressing this issue in an active and concrete manner. Gone is the "well we had a meeting about it" or "we have a list of names of those who might be interested in helping".
When our team performs a "Site Assessment" the first thing we look at is access into the church building. In the old days my church had five or six doors that were open on any given Sunday morning. We had several parking lots, street parking and an off-site lot. Having multiple doors open allowed our congregation convenient access to enter the church; one set of doors opened into the hallway by the kitchen, one into the Children's Church area, one main entrance plus others. The only entry with posted greeters was our main street-side set of double doors. Today at our new facility ALL 1200 Sunday attendees enter through ONE set of doors. This allows our greeters and the security team to observe EVERY person entering our building. I know some people may grouse about having to walk further. We use this response to ease their complaint "Everything we are doing in the way of security is for the protection of you and our children. Do you have a problem with that?"
If someone entering our building piques our interest, for whatever reason, we move to the interaction stage. An interaction can be as simple as greeting this individual and offering your hand in genuine acceptance. The result of that interaction will determine the next course of action. Perhaps the person is a visitor unsure of where to go; direct him to your worship center, help him find a seat and introduce him to others. If the person is belligerent, incoherent or unruly perhaps you'll need to call 911. Ignoring potential danger is never a good idea. The police are trained to deal with all types of individuals; please don't attempt to handle a situation spiraling out of control. Do what you are comfortable doing then let the professionals take over.
The take-away: Limit the accessibility to your church building. Every unlocked door must be manned by greeters and/or security.