The phrase "unshakeable confidence" means having a strong belief in oneself or a situation that cannot be easily disturbed or doubted. It refers to being very sure and secure in what you believe or do. Full definition
It's fleet of foot, it changes direction quickly and assertively and its grip on the road instils its drivers with unshakeable confidence in the car beneath them. (motoring.com.au)
Our liberal elite is full of people whose unshakeable confidence in.... (firstthings.com)
Obese people should have unshakeable confidence when it comes to fat people dating, they don't have to make an apologize to themselves for the weight, but they should embrace it and realize that weight doesn't have impact on self - worth, they have the ability to love and be loved as well as others. (fatpeopledatingsite.com)