HIR,
When we discuss the origin of nursery rhymes, we use the same discipline we use to test the claims of Jesus Christ in the Bible - historical science.
Christianity is an historical religion and the Scriptures need to be tested according to the principles of historical investigation to determine if the Bible is reliable.
This harmonises with the definition of faith in Hebrews 11:1 (HCSB), 'Now faith is the reality of what is hoped for, the proof of what is not seen'.
I consider it is necessary to demonstrate our faith is founded on fact and John 20:29 doesn't refute that. Faith is not a leap of faith but a demonstration of the reality that is hoped for, with 'proof' of what is not seen.
It is faith with foundation in facts. The Christian revelation, recorded in the Scriptures, happened in time in a secular world. When God came to earth in the Incarnation and after the Resurrection,
After he had suffered, he also presented himself alive to them by many convincing proofs, appearing to them over a period of forty days and speaking about the kingdom of God (Acts 1:3 ESV).
You cited John 20:29. If you read this verse in the context of 20:24-29, just prior to John providing the purpose for his book in v. 29, doubting Thomas wouldn't believe the other disciples' testimonies of the resurrected Christ.
What did Jesus say to Thomas? 'Just believe'. No, he provided objective, current proof of his resurrection after 3 days. Thomas wouldn't believe until the facts were exposed - put his finger into Jesus' nailprints and thrust his hand into Jesus' wound in his side.
Did Jesus say, 'You doubter. Get away from me'. No, he provided him with the practical and historical evidence Thomas required.
Acts 17 and Paul's witness on the Areopagus demonstrate Paul's evangelistic strategy of providing evidence in proclamation of the Gospel. His was not a call to faith without facts.
Oz