I’ve posted this before (a while ago) – I hope it’s some help…
It has to do with trust…
For some, it is baby steps, at first. For others, it can happen all at once. Some resist but finally accept, and many reject and refuse out of hand. It is definitely personal and experiential (Spurgeon would say ‘experimental’, in 19th century English
) and there can be counterfeit experiences (as well as counterfeit witnesses), and it is not all just intellectual. I, for example, could not tell you date, hour and minute when I became a Christian. There are probably some Christians who would doubt that I even was a Christian and find my faith suspect, since there was no conscious ‘decision’ on my part that I can point to. There can be false ‘decisions’, as well.
When I was a child, I freely accepted the testimony that that Japan existed. I was given it from trusted sources – my parents, teachers, pictures, books, maps and globes. I was a ‘believer’ in the existence of Japan, or maybe more accurately a ‘believist’, a ‘Japanist’, making a somewhat esoteric and technical distinction. Now that I have been there and have seen it firsthand, I am not going to deny its existence, and I am a ‘believer’ – a ‘Japaner’.
A believer, then, is someone who has had something irrefutable happen in their life experience and which they will never deny as being legitimate evidence. That evidence can be as personal and intimate as a recognition of a change in heart – a change in their heart’s desires and a willingness to trust and to be obedient, but it can also include [empirical] events that can be documented. Either can certainly be denied as being evidence by others, as flat earthers deny any and all evidence that the earth is spherical, but denial does not constitute proof of the contrary fact. There are many who count themselves as believers, or say that they used to be believers and have ‘deconverted’, when in fact they are now or used to be merely ‘believists’.