When I was growing up, I thought God ‘speaking’ meant he literally spoke – one could hear His voice, like any other, although perhaps only oneself could hear it (it was ‘subvocal’). I never heard any such voice, however, and so concluded this was a useless idea, and nonsense.
Old idea: God speaks to people in a way such that they hear Him as a human voice, which clearly almost never happens, and so is useless.
It turns out that Christians don’t mean this when they talk about God ‘speaking’ to one. A different take is:
New idea: God speaks through a specific kind of intuition, or through events that occur which point (are signs) to something.
So, for a Christian, developing a ‘relationship’ with God often involves developing an ability to sift through their intuitions, note which ones probably come from God, and then what they mean. They become good at this by noting whether the intuitions turn out to be good ones or not, and then refining their perception of their intuitions (intuitions that come from God, so the idea goes, will be of a certain sort, or have a certain kind of feel to them).
It also involves seeing ‘signs’ in the natural world – through people or events – that point towards God’s intentions for something one should do. For example, they will repeatedly run into an image where it seems unlikely for them to have done so. (Similarly, the word ‘miracle’ in the English version of the New Testament is often translated from a word that means ‘sign’.)
The intuitions and signs often come in consequence to ‘prayer’, itself a vague word that contains many practices in Christianity. The basic notion, though, is that Christians can develop certain practices for increasing communication with God, and in particular practices for listening so one can understand what God is ‘saying’.
This makes a little more sense, and seems more plausible in that people do have intuitions that occur in response to prayer or what have you and that they attribute to God (whatever their source), and which turn out to be useful, and that there are various events in Christians lives that they could interpret as having more significance than is typically given to such events from a secular framework, and which, similarly, upon following up turn out to be useful.