Atheist here (if religion makes people less afraid of dying then that's great I suppose, but let's face it- it's all bullshitty wish-wash). I'm not trans, but I'm trans-supportive and anti-TERF. And I like to suck cock if that matters.
I don't really think humans can change sex, but TERFs are cunts (you've got JK Rolwing, Grahem Linerhan, a bunch of middle-aged ugly old hags yuck) and people who are TERFs also tend to also be homophobic, racist and hate anyone who isn't white Christian and local. Just take one look at the feminist board on bumsnet, holy fuck that's messed up.
So I became a trans-ally to make sure I distance myself from those old creeps.
That's my take on this whole thing.
edit, I also believe the T belongs with the LGB. TERFs like to pretend gay and lesbians are TERF. Trust me the vast majority are not, go to literally any gay bar or gay pride event in Britain and it and the people there will be trans-supportive (unless a small number of TERFs turn up to cause trouble).