I am of the opinion, that opinions can change.

If someone has an opinion that can not change i would classify this a belief, not an opinion.

This is as for opinions being based on the sum of the available knowledge regarding the matter and as knowledge is something one can gain or less commonly lose, they are of a variable nature.

Beliefs on the other hand are of an ideological, humanly irrational nature.

It is not that beliefs can not change, but they will not change based on few points of knowledge, rather drift over time, just as any aspect of the human experience will drift as time passes.

Now that I have expressed my opinion on the variability of opinions; that i hope you are able to understand that any writers stance on any matter is subject to change.