"all mankind" does not mean every man woman and child past, present, & future.
If it said 'every man' I would have a bone to pick. Mankind is far from every man.
Furthermore, there is a distinction made between "all mankind" and the object of the application which is "our" and "us."
Quote:
| redeem our body and soul from everlasting damnation, (c) and obtain for us the favour of God, righteousness and eternal life.
|
I don't see how it would be teaching unlimited atonement.