Over-kill is the equivalent of using a hammer to crack a nut. To 'over-kill' in a particular situation is to go to an extreme, to 'over-react', in order to accomplish an otherwise commendable goal. Cracking a nut is fine; using a hammer might seem impressive but it is probable that the resulting innards of the nut will be either scattered to the four corners of the room or smashed to pulp.
It is my growing conviction that 'Over-kill' is setting in among conservative Christians in America. Perhaps you'll recognise the same phenomenon closer to home. While I presume that my theologically conservative credentials are assumed because I am writing for Evangelicals Now, it is perhaps nonetheless worth stating what to me and anyone who has heard me preach is obvious: I am a theological conservative. To say that I am somewhat right of Attila the Hun theologically speaking might not be a 'nice' way to put it, but you get the idea.
So this is not a remark from an enemy of the conservative evangelical cause, but a friend. An insider, I guess, to some degree. Nor is it to deny the equally true truth that there are parts of American Christianity which remain radically liberal. What is known as 'Open Theism' (the idea that God changes with time) is a current theological battle underway whose defeat is a crucial aim of all who love biblical Christianity. There are other examples we could enumerate. Let us take it for granted that liberalism still exists, as does its younger cousin 'moderatism', or its elder uncle 'liberal evangelicalism'.
