Neither of these two judges was either Catholic or probably very religious at all, so that might be part of why they thought the way they did. What are your thoughts about those two books, if you care to elaborate on your feelings about them?
First of all, Dante is a poet, the Divine Comedy is an epic poem, and I would guess that one’s enjoyment of Dante - especially of the second two parts - has about as much to do with how much one appreciates good poetry as it does with how spiritual one is. The person who will enjoy the book *most *is someone who loves both poetry and theology, as Dante obviously did.
I’ve spoken to several non-Christians who felt that the Purgatorio was the most interesting of the three sections. I think that might be at least partly because the souls in the Purgatorio are in a state of transition, of change (as are we). Good has ultimately won the battle there, but there is still evil that needs to be purged; there is still a struggle. Dante himself goes through a process of purification in this section and there are serpents, guardian angels, an earthly paradise, and Dante walks through fire.
In the Paradiso, Dante meets a number of saints - including Francis, Dominic, Clare, Thomas Aquinas, Paul the apostle, and finally - after being blinded by the intensity of the light of glory, which increases the closer he comes to God - he is questioned about faith, hope and love by the apostles Peter, James and John respectively; then he regains his sight and sees the Blessed Virgin. He meets various figures from Italian history. Mostly, he has theological conversations with the souls in Heaven. Someone who has zero interest in theology and spirituality and is also not a poet will not find much to interest them.
However, I dare to say that the Paradiso is in every way the most ambitious of the three parts - it is easier to write about vice than about virtue, easier to depict suffering than glory, as Dante is very much aware - and that it is astonishingly successful. The poetry is sublime (especially if you can read it in the original Italian - English translations can never do it justice). Dante, and the reader with him, is drawing nearer and nearer to God, and this is exciting. The book ends with Dante seeing the Holy Trinity.
I’d like to just share a few quotes.

I won’t quote the theological conversations, even though I personally find them interesting, but just a couple of the images of Heaven so you get a taste.
In the first quote, Dante is with Beatrice. She is a glorified soul who has been appointed to guide him through Heaven. Dante is gazing at her face, which has become increasingly bright over the course of their journey. She now tells him to look at the new place they have come to. Dante writes:
“The man who knows just how my vision pastured
upon her blessed face, might recognize
the joy I found when my celestial guide
has asked of me to turn my mind aside,
were he to weigh my joy when I obeyed
against my joy in contemplating her.
Within the crystal that - as it revolves
around the earth - bears as its name the name
of that dear king whose rule undid all evil,
I saw a ladder rising up so high
that it could not be followed by my sight:
its color, gold when gold is struck by sunlight.
I also saw so many flames descend
those steps that I thought every light displayed
in heaven had been poured out from that place.” (Canto XXI: 19-31)
There is so much in this short passage! I won’t comment on it because it would make this post even longer, though.
Dante’s first glimpse of God is as a point in the distance surrounded by light, a “Point that seems enclosed by that which It encloses” (Canto XXX10-11). Such a striking and apt image - especially in context - when we consider that God is everywhere, all-encompassing, but also at the center, and within our souls. Later, as he draws closer, Dante sees the heavenly host as a rose reflecting and reflected in the light of God:
“There near and far do not subtract or add;
for where God governs with no mediator,
no thing depends upon the laws of nature.
Into the yellow of the eternal Rose
that slopes and stretches and diffuses fragrance
of praise unto the Sun of endless spring,
now Beatrice drew me as one who, though
he would speak out, is silent. And she said:
‘See how great is this council of white robes!’ …
So in the shape of that white Rose, the holy
legion was shown to me - the host that Christ,
with His own blood, had taken as His bride.”
(Cantos XXX-XXXI - ellipses indicate places where there is text that I didn’t quote)
If nothing else, read the last canto of the book, in which Dante sees the Trinity. The last few lines always make me want to weep and sing at the same time.