You might like to sign this petition about the #MTRsues issue.
OTOH, you might not. I did, in this case, but I expressed a reservation in my comment.
I've discussed before - though I'm too lazy to dig it out - my frequent discomfort about petitions, manifestoes, etc., which often contain more points than I think are strictly necessary, and often contain specific points that I don't entirely agree with or am not sure about, and which go beyond whatever has me signing the petition in the first place.
In this case, the main point is that intimidatory use of defamation law to stifle debate on matters of public interest is a Bad Thing. A Very Bad Thing. It's not necessary to go further and say whether defamation law should itself be reformed (and the petition doesn't talk about that) or whether public figures should or should not come clean about their religious views (the petition does get into that, but I don't see it as necessary ... and my views as to what disclosures people should make would probably be both complicated and tentative).
Whether or not a public figure has come clean about her religious views, someone who joins the dots and makes comment should not be vulnerable to a defamation action. In the case of Ms Tankard Reist, you don't have to be Sherlock Holmes to work out that her particular parcel of issues and views looks like those of someone who has been influenced by conservative Christian theology of some kind. Whatever her theological position may actually be, that's how it looks from here.
Anyway, if you agree with it, or agree with it in substance, do by all means sign the petition.