a- My point is that Jesus said that the miracle of Jonah would be his miracle, and the miracle of Jonah was that he did not die despite being in a sure death situation.
b- My point is that if God answers the prayers of ordinary people who pray to Him sincerely it is not likely He would ignore the prayer of His anointed one especially when his anointed one prayed so earnestly and desperately that his sweat was as if they were drops of blood. In fact Hebrews 5:7 says that because Jesus was a righteous man, God heard, meaning answered, his earnest prayers. It says, “Who in the days of his flesh, when he had offered up prayers and supplications with strong crying and tears unto him that was able to save him from death, and was heard ("had his prayers answered” in some versions) in that he feared (“because of his reverent submission” in some versions);”
c- My point is that crucifixion was designed to be a slow death that could take days. In fact it sometimes took so long that even the Roman torturers got tired of waiting and broke the legs of the victims to speed up the death. Jesus was on the cross only for a few hours and did not have his legs broken. Death by crucifixion in such a short time was almost impossible. Pilate was amazed too, and he was aware of the circumstances you mention.
d- Here you have got my point when you say "There was no medical certification of the death of anybody else either back then" and therefore given the fact that Jesus was on the cross only for a few hours it is very likely, in the absence of such medical certification, that he was not truly medically or clinically dead.
e- In the case of Lazarus our starting point is that there are no circumstances raising any possibility that he might not have died. So in his case it is a more clear cut case of resurrection. In the case of Jesus there are all those circumstances leaving a lingering possibility that he did not die. This possibility is given strength by the fact that Jesus does not say in his reported sightings that he had died or that he was a resurrected person.
I'm not for a minute saying don't join the Christian world in observing the Memorial of Christ's death. I'm just saying that for me there are just too many indications in the Bible itself that Jesus probably didn't die.
Slartibartfast 