I tend not to believe in coincidences, but from a practical standpoint:
Two water molecules in the same glass of water may call it coincidence when they collide; however, a scientist observing the molecules through the glass finds it perfectly sensible that two water molecules in the same container of liquid water should interact (rather than a molecule of water colliding with a molecule of salt, or dirt, or orange juice, which is not likely to be in the glass of water).
This is essentially the nature of entropy so far as I understand it.
If you and I collide – or if this or that occurs – we may feel inclined to label this “coincidence” only because of our limited viewpoint. An observer with a broader scope may find it perfectly sensible that two like-minded individuals – who have dwelled within a singular, similar specimen of earth and life – should collide.
However, I have a friend who also does not believe in coincidences, but for a completely different reason. He attributes the aspect of sensibility to his deity:
Two similar molecules in a singular specimen – this occurrence may be incidental. However, the magic that the two particles should collide – he believes – far surpasses the realm of both coincidence and incidence.
The magic that the two particles should collide – or not – is what we are, as of yet, unable to explain, and insofar as we seek to understand this magic through science or reason, we will find a paradox of infinitely more miniscule coincidences that we cannot explain.
A wise-minded scientist may call this entropy.