How we change what others think, feel, believe and do
Conversion to another set of beliefs may be sudden or it may happen slowly over a period of time.
A person who is converted to a different set of beliefs over time takes a very different approach to the person who converts suddenly.
They have a need for truth more than certainty, gaining their sense of control through the certainty of understanding rather than the certainty of blind belief. They may thus prefer to question arguments rather than accept external authorities. They may be cynical and untrusting, needing to be persuaded by reason rather than by assertion.
They will see the world in shades of gray, rather than black and white, and hence are able to change their beliefs one step at a time. They may be able to hold both beliefs simultaneously, even if they are diametrically opposed, either by compartmentalizing their thoughts or by having a worldview that sees things in terms of possibility rather than certainty.
A key trick in converting incrementally is to pile up the evidence one step a time. Giving a lot of evidence at once is likely to result in the person feeling overloaded and hence ignoring all of the evidence or at least a significant portion.
If attention is paid to the stress people are showing from receiving new information, then the right point at which to stop can be found. This may be determined with experiments in non-important areas.
An effective way of providing evidence is through direct experience. If a person sees, hears or feels something first-hand, then it is far more difficult for them to deny this than if they are told about it second- or third-hand.
Even after an experience, the person may not convert or even take a small step. In this case they probably need time in which to reflect on the actual meaning (to them) of what they have heard or have experienced.
Reflection can be enabled by giving the person time to think. It can also be encouraged by open discussion and 'musings' that nudge them in the right direction.
When they have made sense of their experience, they still need to integrate this thinking into their current schemas (or 'mental models'). Again, this needs time, and focused conversation may be used to uncover the relevant schema and subsequently help them fit the new ideas into this framework.