I would scrutinize the /etc/passwd contents over and over until my tired eyes finally saw the problem. Eg. /bin/false for a shell or something.

Have you tried logging in to a non-GUI, local console (eg. CTRL-ALT-F2) ?
Network logins, and display-manager (GUI) logins have additional inconvenience ("security") layers that need bypassing by default.

Other than that, the problem could be with the SELinux (aka "the NSA") configuration. I avoid SELinux, so not much help to you there.