We first see the word "mark" in Gen.4:15 after Cain murdered, lied, then pronounced that he was not his brother's keeper. The earth cursed Cain: he lost his ability to farm. He and his followers became fugitives and vagabonds, on the earth. The "mark" is there for others to see the fruit, and avoid.
In Matt. 13 concerning the "Wheat and the Tares" we are instructed to "Let both grow together" [I.D. and leave alone]. Judgment has been pronounced on Satan, and the angels that followed Him: all others are "who-so-ever-will". Matt.18:11 For the Son of man is come to save that which was lost.
Rom.16:17 Mark them which cause divisions and offences contrary to The doctrine... And avoid them. This "Mark" is to observe, pay attention to. Avoid = turn away, shun. Followers of Christ Jesus that can discern the time, understand that there is no time for foolishness.
Phil.3:17 The Apostle Paul is saying Mimic me as I mimic Christ. "Mark" those that are not walking in The example. This is why it is easy for wives to submit to their husbands-that "love their wives, as Christ loves the church".
We know-or should know that we are in the world[cosmos] on assignment. The world[chaos] that belongs to Satan will be dealt with. What is the reward for sacrifice? Matt.19:29 - it will be restored; plus.