You can only speak with AUTHORITY when you speak from EXPERIENCE. The world is full of educated, brainwashed zombies who think that they know everything but they know nothing because they don't have practical experience. They just speak from what they have heard and read, hear-say, they have NO AUTHORITY. And so there are many Christians who profess that they are disciples of Jesus Christ but they have no authority because they don't know Jesus Christ. They have NO TESTIMONY.
It is only if you have met Jesus, if you follow Him, obey Him, walk with Him and HEAR FROM HIM that you have AUTHORITY because you can only DO what Jesus commands you to do with authority IF YOU HAVE HEARD FROM HIM, not from ASSUMPTION.
Many Christians ASSUME that certain promises that they read in the Bible are theirs, that it is their INHERITANCE. They live by ASSUMPTION, they ASSUME things but they do not know Jesus, they have not heard from Him, they live in a dream world, MAKE BELIEF. They believe certain things that they have read and heard but they have not experienced the power of God. They have not experienced a relationship with Jesus Christ. They have not experienced miracles happening in their lives. They have not seen the hand of God moving, they cannot speak with AUTHORITY because they don't know Jesus Christ.
If you don't know Jesus and do not hear from HIM you cannot speak with authority, Many Christians ASSUME and PROCLAIM, CONFESS that they are SAVED but they don't know Jesus, they HAVE NOT HEARD FROM HIM whether He is pleased with THEM, they just ASSUME and they cannot speak with authority. It is only when you have been at the throne of God (in prayer), when you have been with Jesus, when you have heard from Him, when you walk with Him that you know where you stand, that you know your Lord and Master and that you can SPEAK WITH AUTHORITY because you have heard from the King.
Do you WALK WITH the King? Do you HEAR FROM the King? And can you speak with AUTHORITY from your TESTIMONY, from your EXPERIENCE, from your WALK with Jesus Christ or are you just ASSUMING things? Get to know Jesus for REAL, walk with Him, HEAR from Him and then you will speak with authority.
May Jesus bless you.