All people should disclose whether they submit to Allah or not. Those who are against us are our enemies and must be fought. That includes people who call themselves Muslims but who don't lead their lives as such - people who drink, who don't pray, who don't fast, who have constantly changing partners and who are unable to recite the Koran.
The end and aim of spying in all its five varieties is knowledge of the enemy; and this knowledge can only be derived, in the first instance, from the converted spy. Hence it is essential that the converted spy be treated with the utmost liberality.
Why wilt thou be so sottish, such an enemy to thyself, as to prefer puddle-water, and that poisoned too and stolen, before pure living waters out of thy own well?
It is one of the great troubles of life that we cannot have any unmixed emotions. There is always something in our enemy that we like, and something in our sweetheart that we dislike.