It is commonly supposed that the idea of unconditional predestination
is implied in the writing of the names in the book of life. There is
nothing in the figure itself to lead to that, and the text from
Jeremiah suggests, on the contrary, that the voluntary attitude of men
to God determines their being or not being inscribed in the book of
heaven, since it is 'they who depart from God' whose 'names are written
on earth.'
Then, since in the New Testament the book of life is called 'the
Lamb's,' we are led to think of Christ as writing in it, and hence of
our faith in Him as being the condition of enrolling our names.