What does the poet mean by the expression 'sinless flower'?

Directions: Read the following poem to answer the given question.

THE POOR CHILDREN
Take heed of this small child of earth;
He is great; he hath in him God most high.
Children before their fleshly birth
Are lights alive in the blue sky.

In our light bitter world of wrong
They come; God gives us them awhile.
His speech is in their stammering tongue,
And his forgiveness in their smile.

Their sweet light rests upon our eyes.
Alas! Their right to joy is plain.
If they are hungry Paradise
Weeps, and, if cold, Heaven thrills with pain.

The want that saps their sinless flower
Speaks judgment on sin's ministers.
Man holds an angel in his power.
Ah! Deep in Heaven what thunder stirs,

When God seeks out these tender things
Whom in the shadow where we sleep
He sends us clothed about with wings,
And finds them ragged babes that weep!

                      Victor Hugo