Any weddingphotographers here tried an f4 lens with IS in a church ?

Yep but it's not all about the fastness, I see often great weddingpics in the church with wide-angles.
From below with the long weddingdress, some even taken from above in the church, special perspective, don't know if this would be possible in this church, will need to be fast not to miss any other moments

wallstreetoneil wrote in post #17638785
edit: I just looked at your lens sig - you have plenty of fast primes - just slap the 35 1.4 on one body and the 70-200II on the other and don't even think about the 16-35 F4 if moving people are involved in low light

As the others have said, no hesitation. It's contrary to much of the advice you'd normally hear...but a 6D can manage it just fine in my experience.

Go with the flow....

If your shooting in a church with a no flash policy or very low light i would simply use primes. Use your f/4 lens to take certain photos of the "grand" look of the church.

The 24mm prime would work for me as long as you do not get too close to your subjects. This way you can always crop the photo. 35mm you may possibly be too tight in some cases. ....you must go with your "eye" and photographic style.

Ramp up your iso and try to get decent shutter speeds since image stabilization does NOT stop action. This is where even f/2.8 cannot even cut it sometimes and primes must be used.