So there is some discussion going around. . . sort of. . . about how much theological speculation is being done by Lutherans. When it comes to speculation, there are a few things that one must keep in mind.
1 - If you discuss it, be up front that it is speculation. Example, Luther thought Melchizedek was Shem, but he was also honest that this couldn't be proven. Was it traditional - sure, but we are not bound the same way by tradition as we are by Scripture.
2 - When you discuss it, discuss the other side of the matter as well. If there is a matter of speculation, there are usually going to be more than one side. If you bring up your pet side, also bring up the other sides and the arguments for them - especially if you are dealing with folks who are new to the matter of speculation. I don't care whether you think John 6 is Sacramental or not, but if you are going to discuss it make sure you present the idea that it is a debate where decent Lutherans have fallen on both sides of the issue. That way you don't undermine the next guy who may be a fine pastor but happen to disagree with you on a matter of opinion.
3 - Be careful how much you do discuss. I'm a theologian. I like studying scripture and discussing theology. Quirky points are fun - but, they are also open for debate. There are many things that as Pastors that we say on the basis of Scripture that is not open for debate. If you continually bring up things that are debatable, the things that are beyond debate may be less clear. Pick your speculation with caution.
4 - Be kind to others in their speculation. Yes, you might think the person who argues that Polygamy (for those outside the office) should be legal is dumb, but they probably think you are dumb for suggesting the John the Baptist was conceived without original sin (where did that come from?). Let your discussion be cordial, your mocking good natured (I mean, good night, what's with trying to have Christian Superheroes, enough already), and be prepared to have your position not win the day (yeah, and I suppose you are going to argue that the Angel of the Lord was the pre-incarnate Walther too. . . sheesh!).
5. Don't be surprised by these speculations. Everyone's a bit of a heretic in some way. You are too.