Nearly every cell phone these days is capable of livestreaming a church service using the built-in camera and microphone. If you want to step up your game, however, you may need to invest in some technology. Some of the equipment you will need is listed below.
Video
A digital camera with HDMI output. This is what you will capture the scene with. While most DSLR cameras have an HDMI output, and increasingly so do many point and click cameras, these devices are more geared towards taking still photos. Your best bet is to use a digital camcorder purpose-built for video. You will want a camera that can output at least 1080p/30 (a resolution of 1920×1080 pixels at 30 frames per second). While a 4K-capable camera may be tempting (and within budget), it’s not a requirement, and the recordings will take that much more space on your hard drive.
A quality HDMI cable to transmit the captured video from the camera to a computer. My recommendation is to get a good cable, and not the cheapy one from AmazonBasics. Additional cables might be needed for video distribution (e.g. for additional computer monitors, out to a TV in an adjacent room, etc). If you need longer than ~30′, look into converting the signal to SDI or NDI.
While most computers can output HDMI video, you will need an HDMI to USB capture device to input the video signal. This will make the video source appear more or less like a webcam to the computer’s operating system.
Audio
You will need microphones to pick up sounds from the pulpit, the singers/choir, and even the congregation. If you only use one microphone, that can run straight into the audio interface, but for multiple microphones, a multi-channel audio mixer is a must. You will need a channel for each voice or instrument you want to add into the mix. Any instrument or voice that is not mic’d will not make it into the livestream, so don’t forget to mic instruments that don’t normally need additional amplification to be heard in the room (e.g. drums).
XLR cables pass the audio signal from the microphone or instrument into the audio mixer, as well as from the mixer output to the computer. You will need a cable for each microphone/instrument. Unless it has an XLR output, most instruments that get plugged in will need a direct input (DI) box to convert the signal from an unbalanced cable with a 1/4″ headphone plug to an XLR balanced cable. Balanced cables can travel much longer as they are less susceptible to interference.
You will need a USB audio interface to input the audio source into the computer. This performs essentially the same function for sound that the HDMI capture device does for video.
Computer equipment
You will need a decent computer to composite, render, and encode the stream. Most computers made in the last several years should be able to handle live rendering of a 1080p/30 stream, especially if they have a video card with hardware encoding. If not, the main processor and memory will have to perform the task, which can make the rest of the computer sluggish. I recommend a Core i7 processor, 16gb memory, and an SSD drive for storage.
Extra video monitors always come in handy. You may want one facing forwards to show people what the camera is looking at or what the stream video looks like going out. And additional desktop real estate on the computer allows you to have more windows visible without having to switch between them.
Software-wise, OBS Studio is free software and is available for Mac, Windows, and Linux, is easy to use, and is used by millions of users. Using OBS, you can create scenes using various audio/video sources and switch between them as needed during the stream. For instance, you might have a title/end card scene that shows a logo against a plain background. Another scene might be a full-screen view from the camera, or maybe a split-screen view of the pulpit on one side with slides on the other. During the stream, OBS will render the scene at the selected resolution and frame rate, and output it as a stream to a streaming provider or saved as a recording (or both). There is a Discord server frequented by many knowledgeable people for support help if needed.
A streaming provider is needed to distribute your video to the masses. YouTube, Twitch, and Vimeo are all popular options. Keep in mind that some platforms have restrictions on livestreaming, such as minimum subscriber counts.