O Lord, for the sake of them that are deficient do not remove thy word from me!
Neither for the sake of their works do thou restrain from me thy perfection!
Let not the luminary be conquered by the darkness; nor let truth flee away from falsehood.
Thou wilt appoint me to victory; our Salvation is thy right hand. 
And thou wilt receive men from all quarters.
And thou wilt preserve whosoever is held in evils:
Thou art my God.  Falsehood and death are not in thy mouth:
For thy will is perfection; and vanity thou knowest not,
Nor does it know thee.

    The writer is pleading with God to not withhold his word and his perfection from us because of the evil ones that dwell with us.  To do so would let the evil take over the good.  Instead, he asks God, give us victory over the evil, the darkness.  And let the illuminated, the chosen ones, from all quarters (all parts of the world) serve you.  
    But why should God "preserve whosoever is held in evils"?  Because, while many are under the control of evil, usually without knowing it, there is still good in them to save.  Even the evil ones themselves, Satan and the others, must be redeemed in the end.
    God is perfection.  He cannot lie or do evil, so evil never comes from God.  Some argue that if God created Satan and the other fallen angels, and they do evil, than God is doing evil.  That is like saying if a peach tree produces excellent, tasty fruit, but some rot because of the action of bacteria, than the tree produced rotten fruit.  That is obviously not true.  And God cannot take evil back into the Kingdom, so evil must be destroyed in the End Times, which is now, before the world can be redeemed.