Turning back to the OP's post. He made quite a few good points there. More important, I think the example he gave in his post deserves some serious thought.
The first sentence is incomplete since there is no subject and verb, and you used a period for a phrase. Changing the period to a comma doesn't sound correct either.
"Thought" need to be plural: "some serious thoughts".
BTW, speaking of being "over-confident" about one's English skills, some posts here can be cited as the ultimate examples.
The only subject in your sentence is "some posts", but "some post" can't "speak of being confident". The is a typical grammar mistake called" Dangling participles"