Is 1 John 5:7 authentic?

A lot of people do not believe that 1 John 5:7 belongs in the Bible. However, I believe it does.

1 John 5:7 For there are three that bear record in heaven, the Father, the Word, and the Holy Ghost: and these three are one. (King James Bible)

God has preserved this verse of scripture throughout all generations (Ps. 12:6-7), it would not make sense for it to not be authentic. Why would God have it in the preservations of His word for so long?

Latin Vulgate (800 AD), 1 John 5:7 Quoniam tres sunt, qui testimonium dant in caelo: Pater, Verbum, et Spiritus Sanctus: et hi tres unum sunt.

Tyndale Bible (1526), 1 John 5:7 For ther are thre which beare recorde in heuen the father the worde and the wholy goost. And these thre are one

Geneva Bible (1557)  1 John 5:7 For there are three, which bear record in heaven, the Father, the Word, and the holy Ghost: and these three are one.

As for pre-800 AD evidence, the verse is cited by Priscillian (385 AD) "As John says "and there are three which give testimony on earth, the water, the flesh, the blood, and these three are in one, and there are three which give testimony in heaven, the Father, the Word, and the Spirit, and these three are one in Christ Jesus." from Liber Apologeticus.

And here is additional evidence provided by John Henry in his article "The Johanine Comma, Is it inspired scripture"

LATIN EVIDENCE

1) Included in the 2nd century Old Latin Bible.
2) Old Latin MS r has the verse (AD 550).
3) Old Latin MS l has the verse.
4) Latin Vulgate from AD 800 on.

GREEK MANUSCRIPT EVIDENCE: There are at least 10 confirmed Greek MSS that contain the Comma.

1) 61 (late 15th century) (Aland's Text, 3rd edition, p. 824)
2) 629 (14th century) (Aland's, 3rd ed., p. 824)
3) 918 (Aland's; 3rd ed., p. 824)
4) 221 (Listed by Dr. D.A. Waite; Aland's, 3rd ed., p. 824)
5) 2318 (Listed by Dr. D.A. Waite; Aland's, 3rd ed., p. 824)
6) 634 (Listed as confirmed by Dr. D.A. Waite)
7) 636, margin (Aland's, 3rd ed., p. 824)
8) 88, margin, Codex Ravianus, 12th century (Aland's, 3rd ed., p. 824)
9) 429, margin (Aland's, 3rd ed., p. 824)
10) Omega 110 (Listed as confirmed by Dr. D.A. Waite)
11) 635, margin (Holland)
12) Codex Wizanburgensis (8th century) (Cloud)
13) Dr. Waite lists 10 other Greek MSS that are unconfirmed as yet.

GREEK LECTIONARIES (These contained extracts of the New Testanent):
1) Lectionary 60
2) Lectionary 173

WRITINGS AND CITATIONS BY CHURCH FATHERS AND OTHERS:
1) AD 170 - Old Syriac Version (G.A. Riplinger, p. 381)
2) AD 200 - Tertullian quotes the verse (Gill, "An exposition of the NT", Vol 2, pp. 907-8)
3) AD 250 - Cyprian, who writes, "And again concerning the Father and the Son and the Holy Spirit it is written: 'and the Three are One'" (Vienna, vol. iii, p. 215)
4) AD 385 - Priscillian cites the verse (Vienna, vol. xviii, p. 6)
5) AD 350 - Idacius Clarus cites the verse (MPL, vol. 62, col. 359)
6) AD 350 - Athanasius cites the verse (Gill)
7) AD 380 - Varimadum
8) AD 435 - Cassian
9) AD 427 - The Speculum, MS m, a treatise containing an Old Latin texts arranged by topic.
10) Sixth century - Ps-Athanasius
11) Eighth century - Ansbert
12) AD 750 - Wianburgensis cites the verse
13) 1200-1400 - Waldensian Bibles have the verse