For those who are traveling and wish to visit the Church you would be affiliated with "back home", I would suggest putting together a personal website or a FB page etc. There you can post photos of you at your home Church among those you know there. This can also apply to Fraternal Lodges, and other institutions you are
affiliated with.
It's easy and inexpensive to have business cards printed with your name and URL of your site or page. Thus as you travel and enter places like Churches which are now beginning to have "security measures" to screen new faces, you can offer one of your cards such that the security people there can check you out and have some verification of who you are.
You could have all of this in place for less than $15 dollars. BUT you need to take photos before leaving home and going on the road if you haven't already taken to the highways. The websites such as Tripod.com are free,
and the FB, Linkedin, and many others are free.
I received an email just the other day from one of the local Colleges regarding 3D printing for small businesses. As I looked through it I noticed a couple of other free classes that they were offering. One of those was "Church Security". The promo detailed electronic, and physical measures. I'm sure that there are those in many Church congregations now who have Concealed Carry permits and would serve as guards during services or activities. Sad that it's come to this, but in the future travelers who would wish to be a "walk up" guest ("stranger") at a new Church when they are traveling may have something like this to deal with.