Be wise as serpents, but innocent as doves, the Lord said.
I think there is a paradox here, as with many things in Orthodoxy.
Loving the sinner, hating the sin. Recognizing the error of the heresy, and yet also recognizing the bits of truth there in spite of the lies. This is how Orthodox evangelism has always been done. We have two issues at work--a political one and a religious one. In Orthodoxy, politics is (ideally) informed by religion. In Mohammedanism and in Communism, everything is political. Islam preaches a carnal spirituality, Marxism teaches materialism, they are both militant and force an alternative "religion." And yet, many have been drawn to truth reading passages from the Koran and pondering them, and others have been come to faith, as Fr. Dmitri Dudko said, "through the back door" of believing in the non-existence of God. As Orthodox Christians, we are always going to have enemies and be persecuted--from heretics, from unbelievers, from pagans, from Jews, from false brethren, from atheists, from secular humanists, etc. We have no fellowship with any of them, and yet our mission is to live Orthodoxy so that they might see it and be saved.
While Islam and Marxism are full of evils, there are many Muslims and atheists of goodwill. They are repulsed by evil, and yearn for the truth, though they don't know it since their ideologies have put up blinders. As a historian, I cannot say that these groups have always been violent all the time. It is not true. It is not true, either, that Christians have always kept Christ's commandments all the time. I do not believe that all religions teach love of neighbor the way that Christianity does, but I do believe that all people are capable of finding the good, or of following after evil in a capacity as large as the soul.
So, I think, rather than putting people into categories of good and evil or dangerous and less dangerous based on ideology, if we have to categorize, we should look at actions and motives. Much violence has come from ignorance and idleness--on our part and on theirs. The general trajectory of the world is toward an increase of evil, a heightened paranoia, and toward the martyrdom of all who stand for goodness and truth. But, if we endeavor more and more to live Orthodox lives and work for increased goodness and truth, not being suspicious or afraid, but being the first to show kindness, we may just be able to work about a change in heart in those who are afraid of us or see us as enemies. Many times, through this way of action, sworn enemies have been reconciled. And, if not, then we will endure persecution with faith and the help of God. It is what I vowed to do at baptism, to always be ready to suffer and die for the love of Jesus Christ. God rules the world still, and always shall. Neither my worries or political machinations, nor actions of government, can prevent what God's will has ordered. But prayer and love and philotimo can change the whole game to such a degree that the weak become strong, the blind see, and the deaf hear the word of God and believe it.