# The devil is about to throw some of you into prison

"The devil will soon cause others to put some of you in prison" 

# Be faithful until death

"Be faithful to me even if they kill you." The use of the word "until" does not mean that you should stop being faithful at death.

# the crown

"the winner's crown." This was a wreath, originally of olive branches or laurel leaves, that was put on the head of a victorious athlete.

# the crown of life

Possible meanings are 1) "a crown that shows that I have given you eternal life" or 2) "true life as a prize like a winner's crown"