Hi there! I used to work with rehabbing raptors, and that sometimes included little songbirds that needed care until they could be driven to the songbird specialists.
Since it's Monday, hopefully you can take them to a rehabber. Songbird chicks take a lot of intense, specialized care, and the rehabber will have the best formula for them to eat ready and on-hand.
As for the species, did you see the mom and dad feeding the babies? The reason why I ask is, I'm not so sure those are house sparrow babies. The nest is also quite mossy for a house sparrow. If those are a native species, then what the church did - disturbing the nest of a native bird species, is illegal. It is not illegal for you to rescue them if they are in danger and hold them until you get a hold of a rehabber, for a period of time, though the laws on the amount of time you have vary state by state.
Since you say they are eating and pooping, I will assume they are stable and you do not need to go through stabilizing care...They'd probably be dead by now regardless if they weren't and care wasn't provided. Songbirds, especially nestlings, are very fragile. Are they still begging for food? Begging and accepting the crop needle (syringe or other apparatus you use) is the most important sign of good health. Give them a good look-over.
These babies need to be kept warm, just as your chicks do, until they reach fledgling stage. If they are not warm, they cannot process food. It is most important to warm them before you feed them. You should first fashion your own "nest" that you can keep clean for the babies. A small bowl lined with a good amount of paper towels will do. A heating pad will do to keep them warm. Monitor them and make sure they aren't too hot or cold, and adjust from there. They also need QUIET. Keep them away from too much people-noise.
Since they've already pooped, you are ok to feed. Dehydration is not likely an issue, then, it won't hurt to check their skin. Dog and cat food are not a long-term replacement for these types of chicks. Duck food will not do. It's calories right now, though, so better than nothing. If you cannot access specialized songbird replacement formula, you will have to mix your own...There are a lot of recipes online and which one you use honestly depends on what's available to you...Just make sure it places a high importance on animal protein and calcium. Think slightly thicker than butternut squash soup, is how I can think to describe the consistency of what you want. Since you've already gotten them to eat, that's good and you probably already know, but a 1cc syringe is going to be a good crop needle. You're looking for them to make what are called "fecal sacs" at this age. Watch the poop consistency.
At this age, everybody is probably going to eat 0.2-0.6cc. Honestly, the best way to tell is to look down their gullet as they eat and make sure nothing's coming back up. If stuff starts coming up/cllining to the side of your syringe, you know their limit. They WILL overeat if you let them. They're going to need to be fed every 20-30 minutes during waking hours. They will go to sleep when the sun goes down, and wake up when the sun comes back up. When they get to fledgling stage, it's ok to feed them every hour. Keep them CLEAN...don't let food or poop crust up on them.
When they get older, modifications will have to be made to their diet, as well as their housing situation.
Hopefully you can find a rehabber, or have already found a rehabber. Please let us know how this goes!