...should we not give more than just a wink at the claims of a man who claimed to offer us eternal life? More than just a snicker...
At the risk of belaboring the obvious and oft repeated: Most of us have. I arrived at a Christian college as a devout believer and left as an atheist. This change did not happen because of any lack of time spent considering possibilities. The theology I took showed me that my religious views were parochial and unsubstantiated even in a theistic context. The science I studied showed me that those views were at odds with reality. My general life experience taught me that the universe might not behave in accord with my hopes.
Please understand that most of the people with whom you argue have considered the subject in wearying depth, and require no further exhortations to use "more care" in that vein. Rather the converse, more likely.
Capt.