'Confident' in the Bible

I am not ashamed of the gospel, for it is the power of God for salvation [from His wrath and punishment] to everyone who believes [in Christ as Savior], to the Jew first and also to the Greek.

and [if you] are confident that you are a [qualified] guide to the blind [those untaught in theology], a light to those who are in darkness,

This righteousness of God comes through faith in Jesus Christ for all those [Jew or Gentile] who believe [and trust in Him and acknowledge Him as God’s Son]. There is no distinction,

and endurance, proven character (spiritual maturity); and proven character, hope and confident assurance [of eternal salvation].