I wouldn't question the great achievements of the experts over the newbies. And I wouldn't wonder how
the mind can become apprehensive & confused over the rapture because it can be difficult for the newbie to control & maintain the composure, equanimity & concentration...
However, I might wonder what a Christian kind of "rapture" might have to do with pīti; the pamoda of seclusion (viveka) in the internal breath.
Let's not forget that no one can breathe for you, once mindful. Breathing is really an internal process; a process that transcends the external. That is to say that discards and casts out the external (see AN 3.32).
Note also that this internal will have to be discarded too. (See MN 35).
(Note: As far as ajjhattabahiddhā (external-internal) is concerned, SN 52.1, with it's parallel in SA 536 (the cup and the supper) - and which is, (apart from the dubious MN 10,) the only relevant parallel to this concept, with maybe MN122 - might be the best way to tackle the misconception that both the internal & external should be made one) .
This having been said, let's continue with pīti, if you may.
Pīti comes from the root प्री prī, which has
the meaning of gratifaction, satisfaction, and comfort. It has to do with propitiation, or conciliation with oneself in the internality of the breath.
One is delighted as he feels satisfied in the feeling born from the seclusion within the internal body.
This is a mano/body process, with very little citta involved.
And I have a hard time to see into that a "rapture" that moreover, would be difficult to control.
Sounds a bit overdone; as the promise of a filthy rich evangelist.
Now, when one reaches the citta, that has been abhipamoda"ed", as stated in the apanasati sutta (SN 54.13); or explained otherwise in SN 55.40 below:
When the mano is full of joyful contentment, the body becomes tranquil.
Pītimanassa kāyo passambhati.
When the body is tranquil, one feels bliss (in the citta - this is also the result of having abhippamoda"ded" the citta).
Passaddhakāyo sukhaṃ viharati.
The citta becomes established - ready to be totally liberated from mano, which is the orchestrator of the fields of sensory experience (salayatanani) (MN 43).
And when blissful, the mind "establihes itself" (samadhi - https://justpaste.it/5x298
Sukhino cittaṃ samādhiyati.
When the mind is establihed, phenomena become clear.
Samāhite citte dhammā pātubhavanti.
There is no Christian "rapture" into that.
"Rapture" is used by the fool to fool the fools.
Pīti to Sukkha, is mano joy going towards citta joy.
And both have to be cast off in third and fourth jhanas anyway.
It is true that it is not as attractive as some would like to make it look.
But upekkhasatiparisuddhi (purity of mindfulness due to equanimigy) is supposed to be way better and sophisticated.
what the Buddha says.
But maybe an expert would like to tell us, the newbies, a bit more about that.
Some working for the Mara's world; some for the Brahma's world; some for the Unborn.
In this world with its ..., māras, ... in this population with its ascetics.... (AN 5.30).
We are all possessed - more or less.
And what, bhikkhu, is inward rottenness? Here someone is immoral, one of evil character, of impure and suspect behaviour, secretive in his acts, no ascetic though claiming to be one, not a celibate though claiming to be one, inwardly rotten, corrupt, depraved. This is called inward rottenness.”