In one place, Paul himself says that, if Christ had not been resurrected, he would essentially be making God a liar. In another, he says that, if there were no resurrection, they would all be poor men indeed. This would seem to indicate that even some within the Church at least at some point doubted both?
Thomas doubted and Christ was kind enough(?) to show him His wounds. Further, we see Thomas being included among those on whom the Holy Spirit fell at Pentacost.
Also, in Jude 1:22, our author advises mercy upon those who doubt. Given the context, it appears that the doubters are within the Church(?). Could some of the doubters have been doubting resurrection?