but could miracles be an argument for a god?
They could be, depending. Said 'miracle' would have to be something which was observed by different parties and preferably recorded by multiple people, as well as leaving a visible effect for it to count as good evidence. Even then, it would just be evidence of 'something' and not for any religion's god in particular, or even a god at all...
For example, if someone came back to life, without medical intervention, after they were quite clearly dead...that would pretty much defy everything we know. There would be no natural cause for someone utterly dead healing spontaneously and recovering to the point of not having a wound.
Say you have a job, and everyday at the end of your shift you leave by car, and you always take the fastest way home, a certain route that you've taken for about 6 months. One day, for whatever reason, something in your head wants you to go a different way, so you do. You go the longer route for no particular reason, and when you get back home you find out that there was an accident that occurred somewhere along the route you usually take. It would've taken place just about when you reached there, most likely injuring you.
This would be coincidence. Perhaps you went a different way because you forgot something...or received a call, or had another stop somewhere else. Even if the reason was "just because" the fact that an accident happened then doesn't mean they would have been in it, or hampered by it. Nor does it even mean anything all that special. From a probability standpoint, an accident is just as likely on average to have occurred
every other time they drove past that spot the previous 6 months (not getting into different factors like weather/person/car type/traffic flow/day of the week/time of the day/ etc).
We would also have to take this into account. Was there any other time whatsoever that they deviated from the usual path? The problem with this is it is a hypothetical. We can create it to be the most unnatural, yet still logical, problem we want. Real factors aren't taken into account.
So considering that, I've been looking around and I can't exactly find much scientific reason as to what happened, why you would go the other way.
You left the reason open in your example ("for whatever reason"
so I could give you a virtually infinite number of reasons why that one day they took a different path.
Could something like this be the effect of a god?
In your example, it's already extremely dubious that anything out of the ordinary really happened. Accidents happen. People divert from usual schedules every so often. Even if it could be proven that they would divert their path every time something dangerous would happen, it still wouldn't be evidence for a god. It would just be evidence of something we aren't aware of, which could be anything from esp, to fate, to karma, to unnatural luck, to a supernatural entity.
Really, the only 'miracle' I could think of that would definitely prove the existence of a specific god is if it announced itself worldwide, in a way that everyone understood, in a way that we would all hear for no explainable cause, at the same time, specifically mentioned what it was doing, why it was doing it, gave proof to everyone individually that it was a higher power and then predicted an extremely detailed next day that could not be interpreted to mean anything other than what was meant.
While that is asking an absurd amount, it would be inconsequential to an all powerful, all knowing god (which is generally what gods are) and so I see no problem.
"Extraordinary claims require extraordinary evidence" -Carl Sagan