Authority is "the power of rule or government, the power of one whose will and commands must be obeyed by others" (An Expository Dictionary of New Testament Words, p.81).
Matt 8:9 "For I am a man under authority, having soldiers under me: and I say to this man, Go, and he goeth; and to another, Come, and he cometh; and to my servant, Do this, and he doeth it."
Authority in Religion Must Come From Heaven (God) Matthew 21:23-27
When the Pharisees asked Jesus, "By what authority doest thou these things?" (v.23), they showed they recognized the need of authority in religion. When they discussed among themselves the answer to Jesus' question about John the Baptist and said, "If we say; From Heaven; He will say unto us, Why did ye not then believe him?" (v.25), they showed Heaven, or God was authoritative, or to be obeyed.
Some Additional Examples and Passages That Show the Need for Heaven, or God's Authority in Religious Matters
Cain and Abel (Genesis 4:1-8; Hebrews 11:4)
Nadab and Abihu (Levititicus 10:1,2)
Today, Heaven's, Or God's Authority Is Found In the New Testament Scriptures
1) By Direct Statements (Precept).
A direct statement (precept) is a plain statement or command telling us to do something.
For example, concerning the Lord's Supper, disciples are told "Take eat Drink ye all of it." (Matt. 26:26,27)
2) By Approved Examples.
If someone did something and was approved in it, then if we do the same thing under similar circumstances, we too are approved.
The early Christians took the Lord's Supper on the first day of the week (Acts 20:7). If we take the Lord's Supper on the first day of the week, we know we are approved.
3) By Necessary Inference.
From a thing said, a conclusion can necessarily be drawn. From the statement, "And Jesus, when he was baptized, went up straightway out of the water " (Matt. 3:16), one necessarily infers that Jesus went down into the water.
We are told to eat the Lord's Supper. Early Christians ate the Lord's Supper on the first day of the week. Each week has a first day, therefore we can infer that we may eat the Lord's Supper every first day of the week and be correct in doing so.
Generic is defined as "Of, applied to, or referring to a kind, class or group; inclusive or general: opposed to specific" (Webster's New World Dictionary).
Specific is defined as "Specifying or specified; precise; definite; explicit" " (Webster's New World Dictionary).
From Things Lawful, One May Choose Things Expedient
We must be able to give a "Thus saith the Lord" — "Book, chapter, verse" — for the things we teach and practice in religion.
"We must speak where the Bible speaks and be silent where the Bible is silent."
We must not add to the scriptures nor take away from them (Rev. 22:18,19).