ATTENTION: Yes, I have specifically registered with Mumsnet (after lurking for a looooong time) just so I can air my views on this thread.
I am a Christian and I deplore the idea of this or any other play depicting Christ as transsexual. I don't particularly want to get into a heated debate surrounding trans issues per se (although I will be alluding to trans ideology quite a bit in order to get other points across), however I will say that the hypocrisy demonstrated on this thread regarding the OP 'having issues' with transsexuals is rather laughable, and here's why....
Over on another thread I have been lurking on an overwhelming majority of posters who identify as feminists have been gnashing their teeth over the notion of transwomen claiming to be 'real' women and declaring to know 'what it means' to be a woman. There is fury on that thread at the deletions by MNHQ for 'misgendering' transwomen (indeed the last time I looked one of the posters had noted the deletions by Mumsnet Towers had ceased - probably as a result of the ire of some posters who were demanding that from hereon in all posts referencing 'cis'women should also be deleted.)
I'm trying to get to the point: it isn't just Christians that have 'issues' with transgenderism and those of you demanding that the OP ceases 'misgendering' the author of this play (the OP referred to them as 'she') have no right to do so. No right whatsoever. On the Jenner thread several women pointed out that, despite previously demonstrating courtesy to transpeople by using their preferred pronoun, they no longer were prepared to do this as it contravened their fiercely-held belief that not even surgical removal of a penis can change a man into a woman. Moreover, MNHQ are beginning, it would seem, to uphold the rights of 'cis'women to not use 'she' when talking about a transwoman.
Secondly, this goady demand to know which parts of the play were found to be offensive by the OP (the inference being she is an ignorant Daily Mail commentator if she hasn't actually sat in the stalls and watched the performance).....it doesn't matter whether she has seen it or not. When women all over Mumsnet air their discomfort at the ideologies of transwomen nobody interrogates them as to whether they have actually met a transgender person and actually held an intellectual conversation with them to hear of their experience as a 'woman'. Why, then, must a Christian have to have sat through this play to know that it is, to them, an abomination to use Jesus Christ as fodder for Leftie sexual politics.
Someone upthread said that Jesus was killed for holding radical views. Wrong. He was crucified for claiming to be the Son of God; He was killed because He performed miracles and healings that attested to His divine nature and He terrified those who hated His message of equality for Jews and Gentiles alike - that all have sinned and fallen short and all must repent and follow Him.
This is why God sent his son to die on the cross - for the redemption of sins - not to get caught up in the zeitgeist of the time (which is exactly how he is being used in this play; trans issues are everywhere and how better for a transwoman like the author to 'claim' Jesus as one of 'her' own than to suggest he was transsexual. This is nothing new: feminists love to claim Jesus was secretly married). The reason this play is abhorrent to so many people is that it drags our Lord, our saviour, down to man's level. Nowhere in the bible does it allude to Christ being anything other than a heterosexual man; his dietary preferences were not noted, nor the novels he favoured. We are not told what His favourite colour was or what hobbies he indulged in. He came to Earth in the form of man to save sinners; he was man and He was God in equal measure: perfect and entirely without sin. To portray him as transsexual is crass, blasphemous and serves only to denigrate His supreme sovereignty. This is what upsets the Christian who loves Him and worships Him.
Finally, I came on here to thank the OP for her remarkable strength in defending our Lord and saviour in the face of hatred and ridicule and contempt. OP, if you are still reading, please know your public declaration for the glory of God will have pleased Him mightily. You have made some terrific points and I hope you don't feel your loyalty to Christ and your defence of Christianity was lost in the midst of this debate. God will bless you for your faithfulness 
Oh..and before I forget. To those who claim that the author is a Christian (and therefore cannot possible be blaspheming the Christ) I strongly refute that - and to those who would howl in protest saying I have no right to judge others who claim to be Christians I would say this: the bible is very clear what a Christian is. If you google you will find the passages describing what and how a Christian should think, believe and behave. You will also find texts alluding to those who would claim to know Christ but to whom Jesus will say on the day of atonement, 'Be gone from me, I never knew you.'
Nothing about this author's musings that Jesus was transsexual (where in the bible are we told Jesus struggled with dysmorphia??) point to him knowing or loving the Lord. Just as those angry feminists over on the Caitlyn Jenner thread are being permitted to judge who is and is not a woman ('He is a walking insult to women'; 'He's not even transgender, he's an autogynephile'; 'She's a media whore') so must Christians stand up and declare that anyone who blasphemes the name of our Lord Jesus Christ, like the author of this play has done, is not a Christian.