The 'wow factor'; healed amputation
A common sceptical claim is that god seems happy to heal the sniffles but never regrow a lost limb. Of course there are claims of healed amputations and more out there (google one by Smith Wigglesworth for an amusing example), but as always the problem is credibility. The most interesting case I've found is the alleged 'miracle of Calanda,' because of the challenge it presents not only to critics but also to Christians, particularly non-Catholics. The facts not in dispute are that in 17th century Spain a fellow named Miguel Juan Pelicer from Calanda travelled to Zaragosa, lived there for two years as an ostensibly one-legged beggar, then during a trip home claimed and was universally accepted as the recipient of miraculous healing.
The only question is whether his leg was actually amputated in the first place; and on that point, records of the investigation include the formal sworn testimonies of the surgeon (Juan de Estanga) who made the decision to amputate and continued care afterward, a surgeon who helped perform the amputation (Diego Millaruelo) and further confirmed Estanga's testimony, a worker (Juan Lorenzo Garcia) who buried the leg and a presbyter (Pascual del Cacho) who saw the amputated leg and further corroborated details.
https://debatingchristianity.com/forum/viewtopic.php?f=8&t=33692
The challenge for Christians here is that this is obviously far better evidence than there is for the resurrection or any biblical tale; four named witnesses, under formal sworn testimony, less than three years after the amputation, with far less obvious motives for (or evidence of) embellishment or fraud. And yet it's still obviously far from certain that god or 'Our Lady of the Pillar' healed this man; it still could have been a conspiracy to promote a fake miracle... so where does that leave the more dubious biblical tales?
The challenge for critics is that it could have been a conspiracy to promote a fake miracle, but that too is obviously far from certain. Tired, worn-out one-liners about "no evidence" obviously don't work here. Critics, like believers, often seem inclined to adopt a simplistic binary attitude, yea or nay to things they choose to accept or dismiss, but that's more akin to dogmatism than scepticism. The challenge from Calanda (and Lourdes and the other evidence above) is that after initial investigation, rationally we ought to assign some guestimate of probability or confidence in a proposition such as "Pellicer's leg was miraculously regrown" or "This was a fake miracle conspiracy," however arbitrary that may be, because the alternatives are even more arbitrary acceptance or dismissal.
How likely do you think the speculative, explain-away-the-evidence conspiracy theory for the 'miracle of Calanda' is?