Looks like a CSS issue. The 25 pixel margin on the left is a rule in bootstrap.css – this is overridden on your blog posts page by another rule that is applied to .sideBar ul and the sidebar is indeed wrapped in a div with the sideBar class applied.
On the index page that isn’t the case. Would you be able to make a change to correct this, so that the sidebar in that location is wrapped in div.sideBar?
If you need further clarification please don’t hesitate to ask.