'Confidently' in the Bible

“Brethren, I may confidently say to you regarding the patriarch David that he both died and was buried, and his tomb is with us to this day.

This is a trustworthy statement; and concerning these things I want you to speak confidently, so that those who have believed God will be careful to engage in good deeds. These things are good and profitable for men.

so that we confidently say,“The Lord is my helper, I will not be afraid.What will man do to me?”