“Agnostic” doesn’t necessarily mean “unknowable and not subject to testing”. Much more often it has the weaker meaning “not currently known”. There is a house being built across the street. Is there a work van parked in front of it right now? I don’t know. This is certainly knowable and subject to testing—I could get up, walk over to a window in the front of the house, and look. But I don’t care enough to do that, so I continue to now know if there is a work van parked in front of the house across the street. I am agnostic about the existence of such a work van.
“Agnostic” doesn’t necessarily mean “unknowable and not subject to testing”. Much more often it has the weaker meaning “not currently known”. There is a house being built across the street. Is there a work van parked in front of it right now? I don’t know. This is certainly knowable and subject to testing—I could get up, walk over to a window in the front of the house, and look. But I don’t care enough to do that, so I continue to now know if there is a work van parked in front of the house across the street. I am agnostic about the existence of such a work van.