Given that at least 75 people were violently killed in 2016 on church/faith-based property in the U.S., should churches have security teams?

I carry at all times. That's why it's called concealed carry...because you don't know I'm carrying a firearm. Those signs that say no weapons won't stop a criminal, so why should it stop me? I'm making sure I have means to protect myself.

Churches are suppose to be places of neutrality, shouldn't need security . The world has changed a lot since I was younger, and it's changed for worst, not the better.

Unfortunately, it's the world we live in.
I don't think most churches need dedicated security; volunteers from the congregation would probably suffice (as long as they have some training). Some of the mega-churches should probably have a professional team.

I can tell you that security is certainly an issue for churches. But security should not be the focus for the church. I carry a weapon in church. So do others that I know. We're ready to defend the congregation should the worst happen. But the church is the place where anyone can come, at any time. I have joked with others in my church that given my military background I could "lock this place down so well that SEAL Team 6 couldn't get in". We laugh because that mental image is the opposite of what the church should be.
Persecution is part of the price we as Christians should be willing to pay. Some will pay much more than others. When the Bible talks about persecution it doesn't say "if" it will happen, it says "that" it will happen. We aren't called to close our doors to it. We're called to spread the love of Christ in a dying world. You can't do that too well from behind barbed wire. So does that contradict me carrying a gun in church? I don't think so, because I'm just a guy sitting in the congregation who's willing to help when help is needed. That's different than the church itself, as an institution, implementing security protocols. I get that some may disagree with where the line gets drawn and am willing to discuss that. I don't claim to have all the answers here.

My moms pastors wife carries concealed. Churches being a place of neutrality is a thing of the past. The new generation has crossed/ broken so many boundaries that there is no going back. So thank you to the mental defects that have something to prove by proving it at grade schools and churches.

It is too bad. Sanctuary cities, what about Sanctuary Churches or places of worship?

In 2007, at a Colorado Springs church, a former State Parole Officer volunteering as armed security, engaged a man who opened fire on church property. After the church security congregant (a woman) wounded him, the shooter committed suicide. Armed security at churches or other locations where people gather (VFW meetings, etc.) is a very good idea in 21st Century America.

Since I am a retired career law enforcement officer with over a quarter century of service in the federal service alone I suggest you read a book entitled “MORE GUNS LESS CRIME Understanding Crime and Gun Control Laws” by John R Lot. His conclusion is that shall issue laws, which allow citizens to carry concealed weapons, steadily decrease violent crime. He explains that this result makes sense because criminals are deterred by the risk of attacking an armed victim. As more citizens arm themselves, the danger to criminals increases.
He also wrote “The Bias Against Guns: Why Almost Everything You've Heard About Gun Control Is Wrong” This is another very interesting book to increase your font of knowledge.

Well, to quote the Patriot movie: A shepherd must look after his flock, and at times, fight off the wolves. Whether or not the security is official or not should be dictated by the local society. What works in one part of the country may not be as suitable in another. The end game either way should be something effective enough to prevent violations of a church's sanctity. This should also apply to any other place of worship including those of non-Christian religions.

SSG William Jones, I believe that many churches already have such teams, whether official or unofficial, and whether paid (professional) or just members of the church. SGT David A. 'Cowboy' Groth