Only the Word of God
What determines right? What is the standard of truth? The answer is; the Word of God only. Why? “All Scripture is breathed out by God and profitable for teaching, for reproof, for correction, and for training in righteousness, that the man of God may be competent, equipped for every good work.” (2Tim 3:16-17) The standard of truth comes only from this single source. God’s breathed out word equips believers for every good work.
May I suggest some ways that do not determine right? Human reasoning does not determine right. For example; based upon innuendoes Jacob’s sons told him about Joseph, he reasoned in his heart that Joseph was dead; he would go to his grave mourning his son’s death. (Gen 37:12-36) Jacob’s logic was incorrect; it was not based upon truth; Joseph was not dead.
Self sense of right and wrong does not determine right. Many people say “Let your conscience be your guide.” Your sense of right and wrong cannot warn you of sin if it is not first trained in God’s righteousness. Lying is sinful whether you have been taught that it is or not. The Lord hates lying tongues; and Paul tells us to put away lying. (Proverbs 6:17; Eph 4:25)
Paul could say that he had lived his past life in all good conscience even though he had spent a big part of his life killing Christians; persecuting the church that belonged to Christ. He was honest and sincere in what he was doing yet he was wrong in so doing.
Majority does not determine right. Jesus compares the ‘many’ to the ‘few’ by saying that more are going to Hell than to Heaven. (Matt 7:13-14) Do not; I repeat, do not depend upon what the majority does; for your assurance in righteousness! Why? We live in a crazy and insane world where men rush to Hell as if it were Heaven; and; avoid Heaven as if it were Hell!