A secure alternative for the Whatsapp community could or might be this Swiss Threema, a mobile messaging app that puts security first
See:
https://threema.ch/en/ Their claim:
you can rest assured that only you and the intended recipient can read your messages.
.
All security in these days however is only relative security and that is globally so. How far this is true also here I saw when I analyzed the SSL security headers on their very SSL-site, where I saw problems with x-content-type-options, x-xss-protection, x-frame options, content-security-policy with secure headers not being returned. Also not best practices performed on strict-transport-security. So for instance content sniffing stays overall possible also for this service, despite of what the claims, Found these insecurities from their https site analyzed with Recx Security Analyzer.
Authentication however seems for the larger part OK:
https://www.ssllabs.com/ssltest/analyze.html?d=threema.chWhat I think. Stay calm, part of this is fear mongering. It is is all "a hype of the day", at least m.p.o.
polonus