Never attribute to malice what can be explained by incompetence...
The cow and the sheep was important in that culture which served them well before the climate got colder. Judging from their dung heaps they didn't fish much and only the really poor folks ate seals.
If "proper meat" was a status thing and the climate change was slow, they could happily have gone thinking that "next year will be better" while their numbers dwindled. Stubborn Viking settlers? Yeah, I can see that with no problem. Just look at all the later Arctic explorers who could not be bothered to learn from the people who lived in the cold - not necessarily due to religion, but sheer arrogance.
I see your church with my monastery, nunnery and "cathedral with bronze bells and tinted glass windows".
http://www.archaeology.org/online/features/greenland/Also, check out the effect of trade on this little colony: no iron...