Mobile view intrusion????

A client's website has been experiencing issues of possibly being hacked. When I visit the website, http://www.elizapillars.org on my computer the website shows up fine. The problem comes into view when I visit the site on my mobile devices (tablet, phone, etc..). Whenever I visit the same site on the mobile devices, I get pornography, games, etc. rather than the website. How is this possible? How do I resolve the issue?