"Unshakable belief" refers to having a strong and unwavering conviction or faith in something that cannot be weakened or disturbed by doubts or challenges. Full definition
Davies has succeeded at Linklaters through a combination of determination, consistency, and a seemingly unshakable belief in his singular strategic vision. (amlawdaily.typepad.com)
Devoutly Christian Americans hold unshakable beliefs about things they know nothing about?! (religion.blogs.cnn.com)
Unshakable belief between coach, players and community led San Ramon Valley to its first state title (sportstarsmag.com)