Simply put, if we believe that God will ultimately enforce his will by forceful domination, and will eternally torture all who resist that domination, then torture and domination become not only permissible but in some way godly. The implications for, say, military policy (not to mention church politics) are not hard to imagine
...If we believe that Jesus came in peace the first time, but that wasn't his "real" and decisive coming...then we leave the door open to envision a second coming that will be characterized by violence, killing, domination, and eternal torture...This eschatological understanding of a violent second coming leads us to believe...that in the end, even God finds it impossible to fix the world apart from violence and coercion; no one should be surprised when those shaped by this theology behave accordingly.
I always like how, on the one hand, eschatological futurists, like myself, are accused of encouraging people to check out of earthly matters, but then on the other hand we're accused of encouraging people to domination and torture. Darned if we don't, darned if we do.
Chesterton had some interesting things to say about such situations in Orthodoxy, where he gives many and several examples of how the accusers of Christianity will often make the most raging charges against, but that they are often also contradictory, what he called "The Paradoxes of Christianity" (in a chapter of that name). He notes, for example, that while some accused it of being an instrument of gloom and pessimism, they would then turn around and say that it comforted people with false hopes in a fictition god (page 90), or that some accused it of making mankind weak in its teachings of nonresistence and pacifism, others accused it of having "deluged the world with blood".
"I had got thoroughly angry with the Christian, because he never was angry. And now I was told to be angry with him because his anger had been the most huge and horrible thing in human history; because his anger had soaked the earth and smoked to the sun." (page 91)
But his conclusion was that the accusers thought that Christianity was misshapen not because it really was misshapen, but because they were--those who accused it of excessive pessimism were themselves even more pessimistic, for example. The reason why Christianity looked so misshapen to them was that it was in fact shaped rightly, while the accusers were shaped wrongly.
Much the same thing has happened here with McLaren. We futurists have been accused at times even by the author of encouraging people to check out of the world, of telling them to be concerned only with going to Heaven and to not worry very much about the state of the world, and now here we are accused of being so concerned about the state of things here that we will use domination and torture to get what we want.
I would say, though, that in trying to make sense of these contradictions, that it isn't futurism that is wrong, but McLaren.
Consider this, from the quotes above...
This eschatological understanding of a violent second coming leads us to believe...that in the end, even God finds it impossible to fix the world apart from violence and coercion
...but this would only be bad if we are to believe that God is the commited pacifist that McLaren wants us to think He is. If He isn't, though, then the accusation doesn't stand.
If nothing else, one could look at pretty much the entire Old Testament as a refutation of that position. God tells His people many times to take up arms and fight, and even leads them in a campaign of conquest in the Promised Land. If McLaren's position is correct, then God was telling people to commit acts of evil, then God was commanding them to sin.
We looked in the last entry at Revelation 19, at a passage where much that is war-like is said about Christ--in righteous He judges and makes war, He treads the winepress of the wrath of God, an angel invites birds to feast on the slain flesh of those who fight against Him at His coming.
One could as well point out passages in Jude and Zechariah, which tell us that His coming will be a time of violence and wrath and judgment.
In other words, McLaren can insinuate, but he can't prove from the Bible that Jesus' second coming will not be a time of God pouring out His wrath on rebellious mankind. All he can do is paint little pictures of horror which have no basis in the Bible and little in reality, but which are probably more politically motivated then anything else.
Even if he goes the way of preterism, and wants to say that most of the wrath prophecies were fulfilled in AD 70, then it doesn't help him much, because the destruction of Jerusalem and the events leading up to it lead to millions of people being killed. If Jesus' return, literal or spiritual, was at the time that the Romans fought against Israel, it was still a time of war and violence, and doesn't fit his ideas.