Whether Coalition New Zealand is a Christian party or not (the Tamakis themselves are divided), the idea that they, the New Conservatives, an Alfred Ngaro-led vehicle or any religious party can get into parliament does not stand scrutiny

Three Christians walk into a bar. A Catholic, a Presbyterian and a Life Church member... None of them vote for the same party. No, it's not much of a punch line, I confess. But then the idea of a Christian Party isn't much of an idea.

The theory that there's room for a Christian party in New Zealand politics has been tossed about quite a bit in recent years. The idea is that it is a missing piece in the New Zealand political jigsaw, but there's very little evidence to suggest it's a piece New Zealand voters are looking for. Or that it would be able to join together easily with other pieces.

Alfred Ngaro looked destined to test that theory in recent days, with the suggestion from both him and his current leader, Simon Bridges, that he could breakaway from National and lead a conservative Christian party that could become a useful coalition partner for National one day. That was a bad idea badly floated. From the get-go it cursed any party Ngaro might start with the stigma of being a National Party stalking horse. A convenience. A political calculation. It looks cynical, something New Zealanders have made clear they don't like.

Then, today, the announcement that Destiny Church would launch a party called Coalition New Zealand. Hannah Tamaki, the wife of church leader Brian, will lead the party. That's the one smart thing about this otherwise doomed manoeuvre. They join the New Conservative Party in what looks to suddenly be a very busy political space.

Busy, but ultimately barren. Why? First, the maths.

Trying to win and keep and electorate seat in New Zealand – unless you're called Labour, National or David – is seriously hard. Ask the Greens and Kim Dotcom. Or the old Conservatives. Incumbency matters and local loyalties run deep. So the best – probably the only – chance for these new parties is to hit five percent. That means roughly 135,000 votes. 

Now if you look at the 2013 census, you'll see about 90,000 New Zealanders label themselves as members of churches at the pentecostal end of the spectrum. These are mostly fundamentialists, who tend to consider the bible as the literal word of God and take a conservative world view. Even if I'm generous and include the Baptists and Salvation Army in that, I can only get to around 150,000.

Sure, you might rightly say that plenty more in the more mainline Catholic, Anglican and Presbyterian demoninations share conservative views. But my point at the top remains; it is incredibly hard to throw any kind of blanket over the political views of these people. 

Through 2000 years of persecution, domination, reformation and enlightenment, Christians have morphed into all kinds of ideological shapes and sizes. Even supposed fundamentals of the faith – including the fully divine, fully human theology around Christ and belief in his resurrection – are fudgy in many churches. To argue there is a common dogma on which to base a political movement, is (to be biblical) a bit like the blind leading the blind.

Some have tried to tie these parties to conservative views on abortion, ethanasia and drug laws. If they did the same to other faiths, they would likely be mocked for lazy stereotyping. Yes, church-goers would skew more conservative on those issues than New Zealanders as a whole, but these are not defining Christian issues. Not in New Zealand. In short, the chance to pulling the numbers together is miniscule.

Next, the history. Think Graeme Lee and Graham Capill. Think Taito Phillip Field. Think Colin Craig (kind of). Think Brian Tamaki, the last time he tried to start a political party, Destiny New Zealand, back when he was a new and vibrant voice. Yes, this is a second coming for Brian Tamaki, whose first attempt at politics garnered just 0.6 percent in 2005. For many years, both BC (before Capill) and AD (After Destiny [NZ]), New Zealanders have shown severe scepticism when it comes to bringing religion into politics.

Further, those attempts at Christian political parties are a liturgy of scandal and failure. And to remind us of that, the Tamakis today drew on the legacy of the party that has got closest to the five percent threshold, the Christian Coalition. It got to 4.33 percent in the 1996 election, and it offers two pertinent lessons to the Tamaki's Coalition New Zealand.

The first is that even with a sitting MP and a single, united Christian party at a time when MMP was new and faith in the major parties low, the Christian Coalition couldn't get over the line. Second, part of the Christian Coalition's problem was internal squabbling over policy and theology. The two are a potent combination. Fine theological lines can equate to political chasms. While Hannah Tamaki offered Alfred Ngaro a suitably biblical "olive branch" today, the chance of them coming together is next to zero. 

Even in a half hour launch today, the Tamakis couldn't agree. Clearly conscious of the near-impossible maths, Hannah insisted this was not a Christian party, something few New Zealanders will believe. At the end of the press conference, Brian said it was a Christian party, which is more honest, but shows the confusion.

What's more, Hannah said she would not want to over-turn the Marriage Equality Act. Ngaro voted against that and the New Conservatives define "marriage as between one biological man and one biological woman". Good luck squaring that circle.

Finally, you come to the calibre and political nous of the people involved. Hannah Tamaki is likeable, no doubt. She had some nifty phrases today ("succulent chicken") and her mish-mash comments touched on potentially profitable areas, such as more money for poor families as long as it goes on the kids or looking after New Zealanders before immigrants (although that is hardly in accord with Leviticus 18). But she clearly has no idea how to turn cant into policy. And for those who feel strongly about those things, political options already exist.

If you heard Hannah Tamaki's interview with Lisa Owen on Checkpoint this evening, it would have been hard not to write-off Coalition New Zealand as an ill-prepared family indulgence. She had no policy beyond passion for families and wanting abortions to be illegal. She had spoken in her announcement about harmful government policies, but asked to name one she talked about "discrimination" againt her husband, not allowing Destiny's Man Up programme into prisons. Asked about her own policies, she talked about more women getting mammograms because of her daughter's cancer. Asked about funding, she referred to friends funding the party. She said homosexuality is a sin, comparing it to beating a spouse, but that if someone was gay and non-Christian is was "their choice". It shows every sign of being a family folly.

Ill-prepared? Asked about immigration she said 500 people "coming in" might be OK, but 5000 might be "too many". The latest migrant arrival numbers from March total 152,000. Asked whether she agreed with lifting the debt cap to fund welfare, she clearly had no idea what the debt cap was.

There is no united Christian culture on which to build a political movement that could get to five percent. And even if there was, these aren't the people to do it. And even if Ngaro or the New Conservatives might have had a chance (they wouldn't have, but I'm being generous), Coalition New Zealand sinks those aspirations. 

While these voices will get more public exposure as moral issues and conscience votes come to the fore in the coming months, don't expect any of these so-called Christian parties to trouble the scorers. More likely they wither on the vine. 

Three Christians walk into politics? The joke is on them.