Vangard is a free WordPress theme with big image slider and responsive layout. It doesn't include any encrypted links or junk code that could present a security concern for the user.
On the backend of this theme, there is some room for customization. By using the built-in options panel you can upload a custom logo, modify slider settings, change colors, configure banner ads, etc.
After installing this theme, you will also need to download and activate Options framework plugin. It is required for the options panel to appear, where you can adjust various settings of this theme.