If one wants to understand Who axed Acts 8:37, the question should be "Who's axing?"
If one believes the NT Greek text as authored is divinely inspired and thus should not be changed in any way, then any textual variants that omit what is otherwise in the copies of the Greek "autograph" *must* be incorrect. Believing that such a thing is even possible is
verboten, and the inspiration for such ideas *must* be demonic!
If, alternatively, one believed that NT mss are like any other manuscripts that are frequently copied by scribes of various capabilities, one can expect the copies, over time, to develop variants. Phrases are accidentally omitted and when re-copied eventually replaced with paraphrases or reconstructed. There arise occasional errors themselves as they are often quickly corrected on-the-fly in the copying process, or even cross contaminated from other places in the NT. One has to adopt principles when attempting to reconstruct the "autograph," one that weeds out the errors that get introduced, leaving the text that is clearest and simplest.
From my N/A 27 GNT, like the problem of Romans 8:1 being discussed in another thread, the conclusion they made was that the witnesses for vs. 37* were few, late, of unknown history, or a translation into a foreign language, and so likely a gloss based on the theology of a later time. There are variations of this verse as well.**
DCH
*Majority Text editors Stephanus and Scrivener have the text of 8:37 as follows, which I have marked where major variants exist: εἶπεν δὲ [ὁ Φίλιππος] Εἰ [alt. ἐὰν] πιστεύεις ἐξ ὅλης [τὴς] καρδίας [σου], ἔξεστιν [σωθήσει]. ἀποκριθεὶς δὲ εἶπε[ν] Πιστεύω [τὸν ὑιὸν τοῦ Θεοῦ ἐιναι [τὸν] Ἰησοῦν Χριστόν] [or εἰς τὸν Χριστόν τὸν ὑιὸν τοῦ Θεοῦ]
The KJV translates 8:37: "And Philip said, If thou believest with all thine heart, thou mayest. And he answered and said, I believe that Jesus Christ is the Son of God."
The text of Acts 8:37 comes from
E (08, Basel, 6th century),
36 (12th),
323 (9th),
1739 (10th) &
1891 pc (date not stated in either NA27 or UBS 2nd editions I have at hand).
The exceptions marked in the cited text above are:
1) Uncial E (08, 6th cent) adds ὁ Φίλιππος; ἐὰν rather then εἰ; adds σωθήσει; reads εἰς τὸν Χριστόν τὸν ὑιὸν τοῦ Θεοῦ instead of τὸν ὑιὸν τοῦ Θεοῦ ἐιναι τὸν Ἰησοῦν Χριστόν against uncials 36 (12th, although some mss omit τὸν before Ἰησοῦν), 323 (9th), 1739 (10th) & 1891 (not stated), so IMHO this is likely the original form of this variant;
2) Minuscule 323 pc (11th cent., pc = a reading that varies from Maj. Text) omits σου;
3) Minuscule 36 (12th), 323 (11th), 945 (11th) & 1739 (10th) omit τὸν.
** Acts has first order witnesses from papyri
p8 (4th cent),
p29 (3rd),
p33+58 (6th),
p38 (ca 300 CE),
p41 (8th),
p45 (3rd),
p48 (3rd),
p50 (4th-5th),
p53 (3rd),
p56 (5th-6th),
p57 (4th-5th),
p74 (7th),
p91 (3rd) &
p112 (5th).
First order witnesses from the Uncials include
א (01, 4th cent),
A (02, 5th),
B (03, 4th),
C (5th),
D (Bezae Catabrigensis, 6th),
E (08, 6th),
Ψ (044, 8th-9th),
048 (5th),
057 (4th-5th),
066 (6th),
076 (5th-6th),
077 (5th),
095 (8th),
096 (7th),
097 (7th),
0140 (10th),
0165 (5th),
0166 (5th),
0175 (5th),
0189 (2nd-3rd),
0236 (5th),
0244 (5th) &
0294 (6th-7th).
This all means that Acts has witnesses that go back to 2nd-3rd century (101-300) CE, whereas the earliest witness for vs. 8:37 date no earlier than 6th century. All those variants and the dates of the witnesses convinced W&H and NA to omit vs 8:37 as a scribal gloss. Since it serves as an expansion, it is surprising not to see it witnessed by Uncial D (Bezae, 5th century, the "western text"). IMHO, it may have been an expansion created in imitation of the western text type readings, which are usually expansions.
Whew!