Are Americans who attend church at greater risk?

A great deal has been written about the horrible and terrible murder of Dr. George Tiller in Kansas yesterday, but one aspect I have not seen discussed is whether Dr. Tiller put himself at risk by being a regular church-goer. In the interest of full disclosure I am particularly interested in this topic since I also attend church nearly every Sunday morning. More details have been released and it now appears that the murder happened in the vestibule of the church during the church service, where the murderer could have known Dr. Tiller would be because Dr. Tiller was listed as being one of the ushers in the church bulletin.

Dr. Tiller was known to sometimes wear a bullet-proof vest and have security at the clinic where he worked. Was his regular church attendance a fatal security lapse?