Amy, here are the complete lyrics:
I cannot tell how he whom angels worship
should stoop to love the peoples of the earth,
or why as shepherd he should seek the wanderer
with his mysterious promise of new birth.
But this I know, that he was born of Mary,
when Bethlehem's manger was his only home,
and that he lived at Nazareth and labored,
and so the Savior, Savior of the world, is come.
I cannot tell how silently he suffered,
as with his peace he graced this place of tears,
or how his heart upon the cross was broken,
the crown of pain to three and thirty years.
But this I know, he heals the broken-hearted,
and stays our sin, and calms our lurking fear,
and lifts the burden from the heavy laden,
for yet the Savior, Savior of the world, is here.
I cannot tell how he will win the nations,
how he will claim his earthly heritage,
how satisfy the needs and aspirations
of east and west, of sinner and of sage.
But this I know, all flesh shall see his glory,
and he shall reap the harvest he has sown,
and some glad day his sun shall shine in splendor
when he the Savior, Savior of the world, is known.
I cannot tell how all the lands shall worship,
when, at his bidding, every storm is stilled,
or who can say how great the jubilation
when every heart with perfect love is filled.
But this I know, the skies will thrill with rapture,
and myriad, myriad human voices sing,
and earth to heaven, and heaven to earth, will answer:
'At last the Savior, Savior of the world, is King!'
There are two websites I've found that have a lot of hymn lyrics--
http://www.sermonaudio.com/main.asp, at the Online Hymn Search link in the left column, and
http://www.oremus.org/, at the "Hymnal" link in the "Resources" column. This hymn was at Oremus, which also gives you a hokey electronic version of the tune, "Londonderry Aire".