My intent here is not to say anything about 1 John or inter-religious dialogue, but to address this method of dealing with problem passages.
Every word in the Bible was originally addressed to someone else, to some situation other than our own. This point is probably a truism. But, if this is correct, then one of the tasks of those who accept these texts as normative or relevant for today is to ask how those words from the past can "leap the gap" - to use Richard Hays's phrase - and address very different situations. This leap is necessary not only when the Bible seems foreign and obsolete, but also when it sounds familiar and comforting. This leap is an unavoidable consequence of reading words addressed to someone else as addressed to us. That is, this leap is an unavoidable consequence of having Scripture.
If I'm on the right track, then the otherness of the biblical writer's context cannot, of itself, render a text irrelevant for contemporary questions. The question for those who read the Bible as Scripture is not whether a given biblical author speaks immediately to our situation - they never do. For this reason, I don't see how arguments such as the one mentioned above can avoid special pleading.
I am not saying that historical context is irrelevant for reading the Bible as Scripture. Quite the opposite. I am saying that any attempt to limit the significance of a particular passage to its Sitz im Leben implies that there are some other passages which speak immediately and simply to contemporary situations.