When I only have one unread message (or all from the same person), it opens that thread when I open the Messages app. I don't want the thread to open automatically when I touch the message icon, and would rather it opens the list of message threads. What can I do to stop this automatic action of opening the thread?
Silly answer: don't touch it. Sensible answer: presume you are not wanting to send read receipts until you are ready? If so, note that it should return you to the same view you left it in, so to avoid this have a new conversation to a blank sender and select this conversation before minimising/quitting.
I have sometimes wondered about this behavior myself, and wish there was a way to change this.
The short answer is there is no way to configure this.
I have used the notification center (iOS 5, iOS 6) as a bit of a workaround, but obviously this will depend entirely on what you want to do, and doesn't enable you to send new messages or reply to different threads. If you have a device with Siri, you may be able to use that as a bit of a workaround as well.
I have this problem to especially because when the read receipts are on, you dont want them to think that they are ignoring you...best thing ive found is to turn your read receipts off temporarily so you can look at it without them knowing then when you are ready to answer just go turn them back on.