I'm not concerned with enemies of the state, I'm speaking of the spiritual where there are no political boundaries of x hates y. Saul was one of these enemies you speak of and unpacking spiritual wisdom with him could have gotten you stoned, yet he was chosen by Christ to be more and later became one of the most influential Christians of all time.
Witness as the spirit leads you, of course, as you should do in all activities in no different of a manner. We need to be as wise as serpents and as gentle as doves (not the opposite) so don't unpack complex theological insights with someone who's going to stone you like Saul and doing so will be throwing away wisdom and provoking a possible hostile response. Instead give them what they are ready for so they may receive it and grow. Christ tells us to love our neighbour as our self, not to wait for HS revelation in order to know if someone is worthy or not, this level of love is implicit and per-approved by the HS. (and here's a secret: no one is worthy)
So the next time you see one of these "enemies" try and show them a level of love Christ calls us to show. Do so with intention to show them Christ being as gentle as a dove but be strategic and not just soap box preaching so as to be as wise as a serpent.
With Muslims do you know we both love Jesus? Do you know we both believe Jesus will come back to judge the world? That Jesus has power over life and death, he was born of a virgin and ascended into heaven and we are told to obey him? Most also think Christian's believe Jesus is the physical offspring of Allah and Mary having sex and we worship Allah, Mary and Jesus and call them one God. This is just as heretical on our side as it is on their side. Muslims are raised with the wrong perspective about Christ but often that's all they know because that's all they have been shown. Your job is to show them who Christ really is, not to sweep them under a rug and say it's wasted effort.