When developing themes, Elegantthemes takes Security very seriously. They have complete confidence in their team to produce rock-solid themes, but often have their products audited by third party security professional to ensure that nothing slips through the cracks. Recently, they hired Sucuri to do a full code audit and vulnerability assessment of our flagship theme, Divi. Sucuri has studies and scrutinized every single line of code in the Divi theme. In the end, not a single significant problem was found.
WP Web Wizard recommends and uses the Divi Themes in their projects.