Not so many years ago, church doors were wide open to parishioners and guests, no questions asked.

But since a 2015 shooting at a church in Charleston, S.C., killed nine people at a Bible study, church security has become mandatory for most large congregations.

On Saturday, Northland, A Church Distributed, will host a security seminar for Central Florida pastors and church personnel at its campus in Longwood. Seminole Countyemergency management is conducting a similar workshop Wednesday.

Northland decided to hold the seminar now because it received requests from other churches and questions from parishioners in the wake of the November shooting at a church in Sutherland Springs, Texas, that killed more than two dozen people, including eight children and a pregnant woman.

One of the largest churches in Central Florida with a 176-000-square-foot building and seating for more than 3,000, Northland is facing a quandary common to all houses of worship: how to welcome people for prayer and events and also keep everyone safe.

“The idea is that, like all communities of faith, we have to walk a line between security and still being a welcoming institution that people want to go to,” said Andy Brennan, campus security director at the Roth Jewish Community Center of Greater Orlando.

No technique is foolproof, but it’s possible to “take a soft target and make it a harder target,” said James Li, Northland’s security director.

The church seminar, which is not open to the public, will cover concert and other large-event security, how to monitor parking lots and other spaces outside buildings, standard operating procedures, safety on overseas mission trips, child safety and background checks and what equipment to use and avoid.

The county’s Emergency Planning Workshop for Faith-Based Organizations will discuss “active shooters,” suspicious people and what to expect from police and other emergency workers.

Layers of protection are key, Li said. At Northland, a combination of law enforcement officers and private security guards help volunteers and employees direct traffic and assess visitors before they enter the building.

“The point of a church obviously is not to have Fort Knox security,” he said. “It’s to share the gospel of Jesus Christ. We want everybody to come.”

Northland developed safety expertise when it ramped up security about a decade ago as it moved into its current building, Li said. The precautions became even more urgent when former Senior Pastor Joel Hunter became an adviser to then-President Barack Obama. First lady Michelle Obama spoke about good nutrition at Northland in 2012.

“Because we are so family-friendly, we want to make sure they know their children are safe all the way from playing in the playground to taking their class,” Li said.

Other religions also have gotten serious about protection. The Anti-Defamation League, a national Jewish nonprofit, publishes a list of recommended security practices that include hiring a security manager, developing relationships with the police, controlling access to synagogues and Jewish Community Centers, making sure surveillance cameras are working and developing a plan to respond to bomb threats.

Dozens of threatening phone calls were received early this year at Jewish centers across the country, including the one in Maitland, where security has been beefed up even further since the possible danger forced the evacuation of the campus.

The Council on American Islamic Relations provides security and safety training to any house of worship that requests it, said Rasha Mubarak, a Florida spokeswoman. The need became more urgent in 2014 as anti-Islam rhetoric began ramping up across the state and the country and mosques started becoming targets, she said.

A New Tampa mosque was set afire in February, and a Fort Pierce mosque attended occasionally by Omar Mateen, who killed 49 people last year at Pulse nightclub in Orlando, was torched in September 2016.

“Unfortunately, it’s been places of worship that have been targeted,” Mubarak said. “People should go to their place of worship and feel safe, whether they’re praying or reflecting. They shouldn’t have to live in these dark times.”

Seminole County Emergency Management has been offering free preparedness seminars since shortly after the Sandy Hook shooting in December 2012 that killed 20 children at an elementary school in Newtown, Conn., said Steven Lerner, a department planner. The Las Vegas shooting, which in October killed nearly five dozen people and injured more than 500, spurred the county to schedule another workshop, he said.

The department teaches the trademarked “Run, Hide, Fight” model advocated by the Federal Emergency Management Agency and developed by University of Texas at Austin. The philosophy is to escape when possible, hide when it isn’t and use improvised weapons as a last resort. It also teaches tips such as turning off cellphones so they don’t ring and allow a shooter to determine where people are holed up.

“We try and prepare the community as best as possible based on some of the things that have been happening across the country,” Lerner said. “It’s very sad, but the workshop gets good feedback. A lot of people feel very prepared and more aware, so we’re glad that it helps.”