All interesting questions but in order for people to take any of the actions
you speculate about they would have to ignore a basic aspect of Christianity. While
Jesus had a very specific biological identity - male Homo sapiens, Jewish, &c - what
the Word assumed in the Incarnation was not an individual human person (for the person
of Jesus is the Second Person of the Trinity) but human nature in general. Because of
this, there is a proper sense in which all humanity is included in him & his saving
work, & thus that all human beings can be saved through him. The idea that only type
AB people could be saved would precisely parallel the idea that only Jews or males
could be saved.
The distinction someone made earlier between relics and God's word is germane
here too. The shroud, if genuine, should certainly be shown appropriate reverence, &
even if it isn't genuine should be given the same respect as any other image of the
crucified (_pace_ the iconoclasts). But all the scientific investigation which can be
done will not establish with anything more than a high degree of probability that the
blood on the shroud is that of Jesus. In addition, Scripture gives us no divine promise
or command in connection with the shroud. Thus one could not know that the blood on it
is in any way efficacious "with the certainty of faith", and "whatever does not proceed
from faith is sin" (Romans 14:23). In contrast, the efficacy of the Eucharist depends
on the words "this is my body... for the forgiveness of sin", & not on chemical analysis
of the host.
None of this will stop people from the sorts of things you suggest: The same
folks who buy prayer cloths from televangelists & rosaries blessed at Lourdes will no
doubt spend their money freely for cloned blood of (maybe) Jesus. Interestingly, Luther
spoke about such things in the last sermon he ever preached (LW 51, pp.384-5). After
mentioning "secondhand junk" like "Joseph's pants and our blessed Lady's chemise"
supposedly at Aachen and contrasting them with Word and Sacraments: "But these
barbarous, godless people say: 'What, baptism, sacrament, God's Word? - Joseph's pants,
that's what does it!'"
George L. Murphy