1 Timothy 3:16: "Great indeed, we confess, is the mystery of godliness: He was manifested in the flesh, vindicated by the Spirit, seen by angels, proclaimed among the nations, believed on in the world, taken up in glory."
Revelation 1:8: "'I am the Alpha and the Omega,' says the Lord God, 'who is and who was and who is to come, the Almighty.'"
John 1:1: "In the beginning was the Word, and the Word was with God, and the Word was God."
Philippians 2:11: "...and every tongue confess that Jesus Christ is Lord, to the glory of God the Father."
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The text is public domain:
Of the Father's love begotten
Ere the worlds began to be,
He is Alpha and Omega,
He the source, the ending He,
Of the things that are, that have been,
And that future years shall see
Evermore and evermore.
Oh, that birth forever blessed,
When the virgin, full of grace,
By the Holy Ghost conceiving,
Bore the Savior of our race,
And the babe, the world's Redeemer,
First revealed His sacred face
Evermore and evermore.
This is He whom seers in old time
Chanted of with one accord,
Whom the voices of the prophets
Promised in their faithful word.
Now He shines, the long-expected;
Let creation praise its Lord
Evermore and evermore.
O ye heights of heav'n, adore Him;
Angel hosts, His praises sing.
Pow'rs, dominions, bow before Him
And extol our God and King.
Let no tongue on earth be silent,
Ev'ry voice in concert ring
Evermore and evermore.
Christ, to Thee, with God the Father,
And, O Holy Ghost, to Thee
Hymn and chant and high thanksgiving
And unending praises be,
Honor, glory, and dominion,
And eternal victory
Evermore and evermore.
Amen.
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There aren't many phrases in the hymn that come directly from the cited texts, which makes identifying them a bit difficult. Revelation 1:8 is clearly referenced in the phrase "Alpha and Omega." The three temporal elements ("who is and who was and who is to come") are also included, although they don't have the same focus. Instead of talking about God Himself, the hymn names Him as "the source [and] the ending... Of the things that are, that have been, / And that future years shall see."
The line "Ere the worlds began to be" seems to come from John 1:1, specifically "In the beginning."
"Every tongue confess[ing] that Jesus Christ is Lord" from Philippians 2:11 is rephrased as "Let no tongue on earth be silent."
That leaves only the verse from 1 Timothy. This seems to be the main referent, although I'm not sure if every part of the verse is represented in the hymn. Christ's being "Of the Father's love begotten" seems to be (at least part of) the "mystery of godliness" that's described. The hymn's second verse describes His being "manifested in the flesh." The seers' chanting and prophets' promising in the third verse could be the being "proclaimed among the nations." Either the other sections of the verse aren't referenced in the hymn or I'm unable to find them.
