Sunday church is a necessity?
No more or less so than a trip to the bowling alley, or to visit relatives. In all cases, we have determined as a society that the benefits of driving are worth the risk.
It does not follow from society having come to that collective view in relation to driving, that all risks are worth taking, in light of their respective potential benefits. You have to make the case for the specific benefits of circumcision against the risks, not simply refer to another activity, with a different risk/benefit analysis.
Performed properly, infant death is an impossible side effect of circumcision.
If you can back that up with some pertinent data, then please do so. The links I gave suggest that infant death is a rare, yet real consequence of some circumcisions. It is possible that every one of those deaths is as a result of improper procedure, but (a) there was nothing in the links to suggest that this was the case; and (b) even if it were, in an imperfect world, improper procedures will occur, and so the risk/benefit analysis should still be undertaken.
But even where it is possible, infant death is a risk in many things parents do.
Do we outlaw all of those things?
Once again, you have to perform a risk/benefit analysis for each activity - you cannot state that because one risky activity is justified, all risky activities must be justified. That is a false equivalency, and a fallacy.
Let me give you an example - taking our child for a ride in the car to visit church/the bowling alley/grandma is something we see as an acceptable risk, in view of the benefits. Holding the child over a precipice, so someone can take a pic on their iPhone for giggles is something we see as bad, because the benefits aren't worth the risk to the child. Somewhere on that spectrum lies circumcision - what's your considered view as to the balance of risks and benefit, when it comes to circumcision ?