Conundrum

CONUNDRUM

My first is in plumage and also in pyre

My second is in host, a heavenly choir.

My third is just nothing, (your pardon I beg),

My fourth is an ember in which sits an egg.

My fifth is in ink, as seen on this page,

My sixth in inferno, a fiery rage.

My seventh is a cross that is every man's mark,

My whole is a flame that will light up the dark.

What am I?