Our goal is to encourage developers to build software with an awareness of the importance of security, to keep customers safe from the online threats.
You need to find out as a team what the threats really are for your project.
Once your development team has an understanding that software security is relevant for your organisation, and for them, you need to address how to go about making a difference.
But how are they to do that? To answer that, we recommend you first lead your developers to a different question: not how but what.