what does the first stanza of Invictus mean?

Out of the night that covers me,
Black as the Pit from pole to pole,
I thank whatever gods may be
For my unconquerable soul.

Question

what does the first stanza of Invictus mean? 

Out of the night that covers me, 
Black as the Pit from pole to pole, 
I thank whatever gods may be 
For my unconquerable soul.

anonymous · Answer

I thought it might be a comparison to the hardship of life? Since that may be the night. However what is the purpose of the second line.  Also, is thanking the gods meaning some sort of religion based reference or something? I think it might be that the soul is immortal, and that's how it ties it to the religion, which also may be conquerable?

anonymous · Answer

Anybody? AM I right? Is there something more?