Really! Evil people and good people drink the same water, breath the same air, and walk the same roads. Our DNA is commonly human, and we both bleed when we are cut. Evil and good comes in all colors, genders, ethnicities, ages, religions and politics.
The great differentiator is Jesus Christ.
"In this way,
the children of God and the children of the Devil are made plain;
no one who fails to act in righteousness belongs to God,
nor anyone who does not love his brother." 1 John 3:7-10
The great differentiator between the spawn of Satan and the child of God is their overriding desire. Though the child of God stumbles and falls to sin, this man or woman's overriding desire is to do good, to please God, and to be charitable toward their neighbor. Yes, they sin. But it's out of weakness, not strength. The spawn of Satan, however, though capable of outward philanthropic activity, lives fully 'la vida loca' in a life driven by the power to do evil, to deny God, and to outwit, overcome, and defeat his, or her, neighbor.
"Sing to the LORD a new song,
for he has done wondrous deeds;
His right hand has won victory for him,
his holy arm." Psalm 98:1, 7-9
Every morning, whether you are a member of Al-Qaeda or a religious nun of the 'little sisters of the poor,' whether you are a blessed and devout saint or a brutal and devious sinner, you have a choice either to remain the same or to go to the other side--so to speak. No one is entrenched in either camp. God has given us free will to choose the good. We also, however, have weaknesses which make us choose for that which is evil. The spawn of Satan seems to find comfort in afflicting others. And so, they remain the same, or get worse. The child of God, however, either praises God for the grace of their holiness, or repents of a fall from grace and returns to the Prodigal, and Merciful, Father--growing in holiness.
"Andrew, the brother of Simon Peter,
was one of the two who heard John and followed Jesus.
He first found his own brother Simon and told him,
'We have found the Messiah,' which is translated Christ." John 1:35-42
Whether a terrorist or Mother Teresa, the choice is really between Jesus or the devil. This is true because, whether a person is religious or not, 'spiritual' or not, Jesus is the great differentiator. When the child of God chooses for the good, or repents of evil, they are choosing not only for Jesus, but they are choosing in, and with, Jesus, in His Holy Spirit. When the (s)pawn of Satan chooses to do evil, to rob, rape, and pillage, knowingly, or unknowingly, they are rejecting the Crucified and Risen Messiah, and they are choosing in, and with, the father of lies, in the spirit of Satan.
For, in the end, Judgment Day will have been revealed long before the Grand Finale of the Second Coming.