I have been much blessed by the writings I have read by John Bunyan, and also reading of his life. Here was a largely uneducated man, a common tinker, who when it came to the spiritual was a genius. Someone like Bunyan, with little to no real education, gives folks like me likewise has had little to no education, great hope, by how he was used by God, despite his not being one of the learned or well bred, or  educated, and  yet, he too was looked down upon for his lack of  learning  in his day, much as folks can be today.  Charles II asked John Owen, in a disparaging way, why he went to hear the common tinker preach. Owen was an educated man, with a brilliant mind, some would say too brilliant for his own writings to be understood easily by the masses, as his genius often got the better of him, for being able to put his thoughts down, in  a way that the rest of us could easily understand. But Owen replied to the king:he would gladly give up all his learning for the tinker’s power of reaching the heart.

Spiritualizing from the pulpit or otherwise, is generally not well done. It often makes for foolishness and stretching a text of Scripture into the realms of absurdity by what is made out of the text that was never intended. Much more trained minds than Bunyan  have fallen at even attempting this. John Gill is a notable one. Gill, is still appreciated by many, and his name lives  on as one of those Baptists who helped make history, and we still have many of his works in print today. But when it came to the art of spiritualizing from the pulpit, Gill failed dismally at being effective at it.  His exposition for instance of the parable of the prodigal son, in which he tells us the “fatted calf” was that of our Lord Jesus Christ. And again in his exposition of the Good Samaritan, the ass or donkey on which the wounded man was placed, was again our Lord Jesus Christ, and the two pence that  that the Samaritan gave to the host,  are the “old and New Testaments” or the ordinances of the “Lord’s Supper and Baptism” The spiritualizing clearly becomes absurd. And it is not just stretching the text, but taking it out of all context and placing meanings on it never intended. There are numerous other examples besides that of John Gill I could cite where this spiritualizing of the text, becomes absurd and maybe even offensive. But I think the name of Gill and his reputation makes he alone an ample example.  However, the immortal dreamer, John Bunyan, who as most will recognize as the master of the allegory,  made spiritualizing into an art, and a stroke of genius, that not many before or sin have been or will be imbued with, and they will be wise to not even try it, because for the most part, they will wander into the realms of the absurd.  Bunyan had a poetic gift, he also was a dreamer, and this gave him the keen imagination and  insight, to make allegories as living or real examples, and for them to not become absurd.  This is one such text below where his spiritualizing turns into genius

The leaves of this gate or door, as I told you before, were folding, and so, as was hinted, have something of signification in them. For by this means a man especially a young disciple, may easily be mistaken; thinking that the whole passage, when yet but a part was open, whereas three parts may be yet kept undiscovered to him. For these doors, as I said before, were never yet set wide open, I mean in the anti-type; never yet saw all the riches and fullness which is in Christ. So that I say to a new comer, if he judged by present sight, especially if he saw but little, might easily be mistaken, wherefore, such for the most part are most horribly afraid that they shall never get in thereat. How sayest thou, young comer, is this not the case with thy soul? So it seems to thee that thou art too big, being so great, so tun-bellied a sinner! But O thou sinner, fear not, the doors are folding doors and may be opened wider, and wider again after that; wherefore when thou comest to this gate, and imaginest that there is not space enough for thee to enter,  knock and it shall be wider opened to thee, and thou shalt be recieved (Luke 11:9; John 6:37). So then, whoever thou art come to the door of which the temple was a type, trust not thy first conception of  things, but believe there is grace abundant. Thou knowest not yet what Christ can do, the doors are folding doors. He can do exceeding abundantly above all that we can ask or think (Eph. 3:20). The hinges on which these doors do hang, were, as I told you, gold; to signify that they both turned upon motives and motions of love, and also that the openings thereof were rich.  Golden hingest the gate to God doth turn upon. The posts on which these doors did hang were of the olive tree, that fat and oily tree, to show that they never do open with lothness, or slggishness as doors do whose hinges want oil. They are always oily, and so open easily and quickly to those who knock at them. Hence you read that he who dwells in this house gives freely, loves freely, and doth us good with all his heart. “Yea,” saith he, “I will rejoice over them to do them good, and I will plant them in this land assuredly, with my whole heart, and my whole soul.” Jer. 3:12, 14:22; 32:41, Rev. 21:6; 22:17. Wherefore, the oil of grace, signified by this oily tree, or these olive-posts, on which these doors do  hang, do cause that they open glibly, or frankly to the soul.
—John Bunyan on the leaves of the gate of Solomon’s temple.

As one of Bunyan’s biographer’s wrote about The Pilgrim’s Progress:

There is no question of the work of genius in the Pilgrim’s Progress. Taine, the
great critic, says that Bunyan has the freedom, the tone, ease and clearness of
Homer. The first edition of the Pilgrim reveals the fact that Bunyan was a
natural writer, and not a product of the schools. Take his spelling, for instance.
When it came to spelling Josh Billings could not hold a candle to him. We
know that there was a good deal of off-side spelling in that day, but Bunyan
never let the spelling book get in his way. For example, he spelled the word die
in three ways: “die,” “dye,” and “dy”; he wrote for Slough of Despond, “Slow
of Dispond”; “ay” for aye; “bien” for been; “bruit” for brute; and “ray-ment”
and “rainment” for raiment; “strodled” for straddled.
It is said that there is nothing remarkable in doubling the final consonant in
such words as “generall” and “untill,” for that was the seventeenth century
custom, but Bunyan doubles it in such words as “bogg,” “denn,” “ragg,”
“wagg,” and, what is even more unusual, he doubles the medial in such words
as, “hazzard,” “fellon,” “eccho,” “widdow.” He dropped his final e’s, writing
“knowledg,” “bridg,” but he uses the “e” to give the old plural form, making it
“shooes,” “braines,” “alwaies.” He was strong on colloquial expressions and
grammatical irregularities, writing “catched up,” “shewen,” “ditest,” “then for
to go,” “I should a been,” “afraid on’t,” “such as thee and I,” “you was.”
Bunyan did not spell brains according to the dictionary, but he had them all the
same, and all that is needed to produce a great book is brains. You can write
your book with lead pencil on butcher’s paper, spell like Josh Billings, and
disregard punctuation marks, but if you have “braines” or “brains” — either
form will do as long as you have them — a hard-boiled publisher will even
send you a prepaid telegram accepting your book.
It is said that the printer corrected a good deal of the spelling in the first
edition. I wonder if any writer is a genius to his proofreader? [William Hamilton Nelson]

Yet despite his obvious lack in the wys above, his heart and spiritual accumen, made him a genius. The Immortal dreamer, that everyone, Calvinist and any other stripe of Christian alike, all recognize the name of.