In the poem "The Seafarer," how did religion come to Great Britain?Our professor gave us a study guide, and this is the last question but I do not...

Concerning "The Seafarer," Christianity came to what we
now call Great Britain in the sixth century A.D, brought by missionaries from
continental Europe, for the most part.  Celtic and Anglo-Saxon beliefs would have been
popular before Christians arrived, and well after. 

The
poem, I don't think, really deals with how "religion" arrives in Britain.  Specifically,
it doesn't deal with how Christianity arrives.  The poem is a mixture of non-Christian
and Christian thought.  Fate, for instance, is an idea possibly inherited from the
Greeks, who were obviously non-Christian.  The poem doesn't specifically deal with how
religion got there, though.

Thus, I'm not sure exactly what
your instructor is looking for, if the question is worded as you've worded
it. 

Christian thought in the poem is something to be
studied, and something that can shed light on Christianity in Britain, though not the
history of how it arrived.

The didactic, sermon-like
passages in the poem (lines 64-80 and 103-124) are possibly interpolations.  "The
Seafarer" is likely an oral work that was eventually written down by a Christian monk. 
No copyright laws existed then, and the concept of personal ownership of a work
of writing was much different then than it is today.  It's possible that the monk who
wrote the poem down added his "two cents worth," as they say.  The theory is that the
monk writes down the Anglo-Saxon, non-Christian work, and while doing so attempts to
Christianize it. 

The passages suspected of being
interpolations seem to some commentators to lack unity with and relevance to the rest of
the work, and to be different in tone and purpose. 

For a
specific example, the "Thus," in line 64 suggests to me that the lines are something
added by a monk, since thus is like a therefore, and should be the
culmination of what comes before it.  Before this thus is lots of
misery and swearing at the ocean, yet the thus leads to "the joys
of God" and great praise for God, etc.  The suspected passages are extremely didactic,
or sermon like. 

Thus, the poem,
though it doesn't deal directly with how religion arrived, may share light on
Christianity once it arrived.