So 11 disciples saw the resurrected Jesus. They told the 12th, Thomas, about it. Thomas was the only one who had not himself then seen the resurrected Jesus, and said he would not believe the 11 until he, Thomas, also had the same experience. After he did, all 12 had so seen Jesus. But Jesus is reported to have blessed those who believed without seeing--which would not include Thomas or the other 11. By seeing the resurrected Jesus, those 12 disciples henceforth were called special witnesses, i.e., apostles.24 But Thomas, one of the twelve, called Didymus, was not with them when Jesus came.
25 The other disciples therefore said unto him, We have seen the Lord. But he said unto them, Except I shall see in his hands the print of the nails, and put my finger into the print of the nails, and thrust my hand into his side, I will not believe.
26 ¶ And after eight days again his disciples were within, and Thomas with them: [then] came Jesus, the doors being shut, and stood in the midst, and said, Peace [be] unto you.
27 Then saith he to Thomas, Reach hither thy finger, and behold my hands; and reach hither thy hand, and thrust [it] into my side: and be not faithless, but believing.
28 And Thomas answered and said unto him, My Lord and my God.
29 Jesus saith unto him, Thomas, because thou hast seen me, thou hast believed: blessed [are] they that have not seen, and [yet] have believed.
In the Book of Mormon, it is claimed that "And now as I said concerning faith—faith is not to have a perfect knowledge of things; therefore if ye have faith ye hope for things which are not seen, which are true." Alma 32:21. Also, "faith is things which are hoped for and not seen; wherefore, dispute not because ye see not, for ye receive no witness until after the trial of your faith." Ether 12:6. However, Ether 12:6 is at odds with what Jesus did with Thomas. Thomas did not first hope for things not seen (i.e., faith) and have that hope tested before Jesus appeared to him. Rather, Jesus appeared to the doubting Thomas, who received that witness before any trial of such hope by Thomas. The Book of Mormon thus claims that faith and it being tested are prerequisites to a witness, when the Bible illustration belies that. Of course, the Book of Mormon approach gives a 'leader' like Joseph Smith an out--'If you, Brother Jones, have not received a witness, it is because your faith has not been strong enough to hold up when tested.'
Back to John 20:29. Why would one who has not seen something, just hoped for it to be so be blessed beyond those that had an actual witness? Why does Jesus value hope over actual witness? Many assumptions are wrong, but assumptions too are based on not having seen. Why does Jesus prefer humans that will act on a faulty information system (hope without having seen) over those that act reasonably on what they experience with their senses?