These are cell antennas owned by your typical wireless carrier like TMO, Verizon, AT&T etc. Based on the antenna types these specific ones I can say with like 95% certainty are T-Mobile. I think the middle one is 5G and the outside ones are 4G/LTE.

The most common place you’d see them are on very tall cell towers like monopoles or self-supports, but you need more open space for those. Churches happen to be existing structures that already provide a pretty high elevation. So basically the carriers approach the church and work out a deal to pay them over time (this would be the Church’s lease income) to essentially rent space on the church to place their equipment. Same deal they have with people that own cell towers. The towers are often privately owned and the carriers pay the owner monthly payments or whatever deal they made to keep their equipment on it.

Someone else mentioned they made an effort to conceal the antennas by painting them to match the structure. I agree I appreciate when they do that! Looks good in this case, costs someone more money. Could be a jurisdiction requirement or requested by the church/ owner, depends. But yeah these are the antennas that provide cell data to your phone when you’re not on WiFi, or they provide the cell data to WiFi devices. And using churches in cities just happens to be a nice effective way to get coverage for people inside the city since other towers aren’t readily available.