Why is the Son of God called Jesus, that is, Saviour?
Because He saves us and delivers us from our sins, and likewise because we ought not to seek, nor can we find salvation in any other.
Scripture references
Do those who seek their salvation and wellbeing in saints, in themselves, or anywhere else really believe in Jesus as the only Saviour?
They do not, for though they boast of Him in words, yet in deeds they deny Jesus the only deliverer and Saviour; for one of these two things must be true: that either Jesus is not a complete Saviour, or that those who by true faith receive this Saviour must find all things in Him necessary to their salvation.