With the launch of their official manifestos, Britain's political parties have opened their policies up to public scrutiny and analysis. Very few voters – and perhaps very few loyal party members – will whole-heartedly agree with everything their party of choice believes, but what swings our vote is that we agree with enough. As well as the intangibles like whether we warm to the party leader, what our voting habits have been in the past and what our friends think, we're influenced by how we think we'll be affected personally by parties' policies and by the effect we think they'll have on things that matter to us more widely. For Christians, this is likely to include how they'll address poverty and the position of very vulnerable people.

Ah, I know this one. The Right are all stony-hearted old-Etonian plutocrats who enjoy grinding the faces of the poor, and the Left are bleeding-heart drippy liberals who want to take all my money and give it to wasters who can't be bothered to work for a living.

These are certainly the stereotypes. It's more accurate to say that the Right emphasises personal responsibility and the role of families and communities in caring for vulnerable people, and the Left emphasises the responsibility of the state because otherwise too many people fall through gaps in care.

The problem with the Right's approach can be that people who really need help don't get it because someone has wrongly decided that they don't need it. The problem with the Left's can be that people who really don't need help do get it because their welfare system isn't set up to distinguish between deserving and undeserving cases.

Both want roughly the same thing: everyone who can work should be able to and those who can't should be looked after. They have different ways of achieving it.

I think I just about get that ...

Think of the donkey with the carrot and stick. The Right offers a spiked mace and half a mouldy carrot, while the Left offers a luscious, juicy carrot and a twig.

Fair enough. So what do the parties actually say?

The Conservatives intend to take £12 billion out of the welfare budget for working-age people. They will lower the household benefits cap from £26,000 to £23,000 and reduce benefits for drug addicts and obese people who won't accept treatment. They will also press on with universal credit reform, designed to simplify the system and make sure it always pays to be in work.

£12 billion sounds like a lot.

It is. George Osborne has promised £30 billion in 'fiscal consolidation' – ie cuts – during the next parliament, including the £12 billion on welfare. The total benefits budget is £166 billion, but the Conservatives have said that they won't cut the main pensioner benefits (nearly £90 billion). So the saving represents a decent chunk of the remaining £76 billion, which pays for housing benefits, disability living allowance and employment and support allowance (ESA) which helps people with limited capacity for work.

The Conservatives have so far declined to say where this will come from other than cuts to housing benefit for 18-21-year-olds (£120 million), a benefits freeze (£1 billion) and getting more people off incapacity benefits (unknown).

I am not sure what to say about that.

Not saying where the money is coming from is certainly a bit odd, at this stage of the game. However, it is reasonable to infer that most people on benefits should assume their income will be cut, in some cases very sharply.

Someone who is sure what to say is Liberal Democrat leader Nick Clegg, who has said that if there is another coalition he will not accept £12 billion of cuts (he's suggesting £3 billion).

But why do they want to cut so much anyway?

Because they want to eliminate the deficit very quickly and start paying down the national debt. These spending cuts are part of a continued austerity drive. One of the criticisms made by the other parties is that they fall on people who can often barely cope as it is.

So, what about the other parties?

The Lib Dems also want to eliminate the deficit, and also by 2017-18; Labour says it wants to eliminate it at some point during the next parliament. Other parties, like the Greens and the Scottish Nationalists, believe that the time for austerity is past and that the country should start spending again. They think that the deficit will come down naturally as the economy grows.

Back to welfare, though: you've talked a lot about the spiked mace, what about the alternative?

Labour will cap overall welfare spending. It will 'pause and review' Iain Duncan Smith's universal credit scheme, (which everyone agrees with in principle but which has been dogged by operational problems) scrap the 'bedroom tax', look at whether the £26,000 benefits cap should be lowered in some regions and cut winter fuel payments for the richest pensioners. It will guarantee jobs for under-25s unemployed for a year and over-25s unemployed for two years.

The Lib Dems would cap rises in benefits at one per cent a year for two years and would scrap the bedroom tax unless tenants actually refused a smaller property (this addresses the problem that there's often nowhere for people to go if they're hit by the tax and can't afford to stay where they are).

So, no cuts there?

Nothing on the scale of those planned by the Conservatives. However, the idea that if you care about poor people you vote for one of the parties on the Left and if you don't you vote Conservative is too simplistic. Welfare is really important, but it can't be isolated from the wider issues. For example, if an incoming government got the economy so badly wrong that Britain went into another recession and ran out of money again, more people would be unemployed, the welfare bill would rise and sooner or later cuts would have to be made.

The other thing to say is that for people not to work when they're capable of working is really, really bad for them. Unemployed people suffer more physical and mental illness and die sooner than employed people. A Prince's Trust survey from 2014 found that 40 per cent of unemployed young people showed signs of mental illness. So you might think that the drive by the last government to get people working, in part by a very, very tough regime of sanctions – stopping benefits – was a good thing.

On the other hand, many of those sanctioned – and their families – fell victim to a truly inefficient system, as the Churches pointed out, the jobs people previously on job-seekers allowance found were low-paid, and many people just dropped off the radar altogether – that is, they stopped claiming JSA but didn't find work. So as civil servants are accountable to their ministers, there is also a question of competence: as the Churches argued, the system is in many ways not fit for purpose, regardless of the philosophy behind it. 

But can we carry on funding the welfare system on its present scale?

The argument made to various extents by the Liberal Democrats and Labour is that while it's important to cut the deficit, it can be done more slowly without putting jobs, welfare and other areas of the national life so much at risk. They point out that while on the face of it Britain seems to have weathered the last round of cuts well enough, the next round will be even deeper and harsher, and simply isn't necessary. Or, to revert to our original metaphor, you can do more with a carrot than with a stick.

But which is right?

Isn't democracy wonderful?