This is done via permissions from the admin console. Navigating to Admin Console -> Spaces -> Permissions, you will see the access permissions for 'anyone' (guests). By placing a green check in the 'view space' column, your space will be able to be viewed by anyone/guests.
I've been experiencing the same issue the parent had. I am using Clearspace 1.1.1, however I had the same issue with 1.1.0.
Here is what I did:
1. Navigated to Admin Console -> Communities -> Community Permissions
2. Guest users given "View Space", "Read Document", and "Read Comment" permissions
Even with those permissions explicitly set, my users are still presented with the login page instead of the open community.
Clearspace (not ClearspaceX) also has a special system property:
which by default is set to 'true'. You can either delete the property or set it to 'false' and guests will be able to browse your site.
I really wish this (as well as most of the configurable system properties) was clearly documented in the documentation.