Honestly, you don't have to reply to every message.
Select a sample of messages that bring out the most important points, and reply only to those. For the others, you can click on the "You have not yet responded" line at the bottom of the post, as a way of acknowledging that you have seen that post but chosen to not reply.
And pace yourself. If you only have time for 10 replies today, then only reply to those 10 (or whatever you think is a number you can handle). You can come back tomorrow to reply to some of the ones that you missed.
When you reply rapidly, other people will respond to your posts just as rapidly. If you slow down your rate of replies, you will slow down the whole thread to a pace that you can handle. If done with care, you can greatly reduce the pressure that you sense.
Oh, and there's no need to reply to this particular message.
Jesus was a liberal hippie