I’m sorry (not really, but you already knew that), but these shoes and their ilk are not suitable for professional wear in any context.
By all means, buy the shoes and wear them in good health for a good cause on your days off. Just know that they are the footwear equivalent of pajamas and do not adequately communicate the responsibilities of your role in the community. “Oh, hey, I came here in my BEDROOM SLIPPERS to discuss the urgent issues of poverty and hunger in town.”
It’s fine to purchase clothing that speaks to your values. It’s not not always fine to wear them in a professional context.

Not even the eye-watering yellow?
Ummm, honey? Canvass shoes are the ones you wear when asking your congregants for their annual pledge to the operating budget. The ones you showed us are CANVAS shoes.
Oh. Well, I’m sick and on Benedryl so I’m STANDING BY MY SPELLING TONIGHT.
But then canvas shoes could be good canvass shoes (oh dear, our budget is so behind that the pastor can’t even affort real shoes any more – quick, pass the cheque book 🙂 )
Yeah, start wearing those and the congregation may start feeling sorry for you…which is probably not the best way to maintain authority. All that aside, what the heck does this company stand for? Sounds like a feel-good gimmick.
Continuing the gentle wordplay, I say canvass shoes for canvassing would be some kind of sensible supportive boot or walking shoe, for walking miles and miles knocking on doors in the neighborhood for the cause. I have a couple from L.L. Bean (hiker look) and Red Wing (black work boot look), but nothing that looks girly. I have a nice pair of Lenore (pattern by Stephanie Pearl McPhee) in pastel with a lacy border that just peeks over the top of the black boots.
I’m on the side of the ones in the pics at the link as being bedroom slippers. They don’t look constructed enough to make it through a day at work.