Post Excerpt/ Summary

Hello, This is a question/feature request. I wanted to just show the teaser/excerpt of member posts to the visitor. Currently any post under the positive rule will not even show up and the page is just left blank. I think I saw another user make this request in the forum. This how paywall should work. Even in the plugin description it says, "gigaom like functionality." Gigaom actually shows the teaser or how about Paid Memberships Pro plugin? By default it has this functionally.
Work around this is adding URL group, but imaging adding all the URL group.

Is there function that can be added to theme file to achieve this?

MU ninjas, please respond.