The word "authority" means "the right to command or act". Therefore, authority in religion would mean the right to command or act religiously. In the book of Jeremiah, Chapter 10, verse 23, we read, "O Lord, I know that the way of man is not in himself: it is not in man that walketh to direct his steps". We, therefore, see that the human standard for setting authority is wrong. God calls a man a "fool" who would reject the divine standard of authority and trust in his own heart. (Proverbs 28: 26). After Christ arose from the dead, and in giving the great commission, he said, "All power (or authority) is given unto me in heaven and in earth". (Matthew 28: 18). Our authority in religion is in Christ. God has acknowledged him publicly as his Son. (Matthew 3: 13-17). He is now God's mediator and spokesman for the new covenant. (Hebrews 1:1). This is the age in which you and I are now living. The Old Testament, as far as being a law, for us ended with Christ's death upon the cross. (Col. 2: 14-16). Christ has all authority!
In the New Testament we have divine authority for everything we do in religion. The Bible is man's only true creed and the New Testament our only code of laws in matters of religion. Herein, God has given us all things necessary to life and godliness. (II Peter 1: 3,4). The scriptures furnish us completely unto all good works. (II Timothy 3: 15,17). We are commanded not to go beyond the things which are written. Nothing may be added to, or taken from, this established standard of authority. (Rev. 22: 18-19). We must do as Paul urged Timothy, to rightly divide the word of truth. (II Timothy 2: 15).
The word of our Lord as found in the New Testament is our authority in religion today. We are taught that "All scripture is given by the inspiration of God". (II Timothy 3: 15-17). The things Paul wrote were "the commandments of the Lord". (I Corinthians 14: 37). He wrote to Timothy that he might know how to live right. These writings in the New Testament were for us and that we might believe in Christ and accept the truth. God has given these writings to keep us from sin; and that we might know the certainty of the truth of Christianity and as Christians have eternal life. (I John 5:13). Our authority in religion is in Christ and we have his word recorded in the New Testament for our acceptance today.