“For as many as have sinned without law will also perish without law, and as many as have sinned in the law will be judged by the law(for not the hearers of the law are just in the sight of God, but the doers of the law will be justified; for when Gentiles, who do not have the law, by nature do the things in the law, these, although not having the law, are a law to themselves, who show the work of the law written in their hearts, their conscience also bearing witness, and between themselves their thoughts accusing or else excusing them)in the day when God will judge the secrets of men by Jesus Christ, according to my gospel” (Romans 2:12-16).
To rightly divide God’s word it is imperative to identify the covenants God has made. As Paul describes above, prior to the gospel there were two groups of people—those “without the law” of Moses (i.e., Gentiles) and those with the Law of Moses (i.e., Jews).
With Christ and the new covenant He inaugurated by His blood (Matthew 26:28), all humanity—Gentile and Jew—were amenable to one covenant (Ephesians 2:11-18). Every creature needs to hear the gospel (Mark 16:15), and all men everywhere are commanded to repent (Acts 17:30) and be baptized (Mark 16:16) in the name of Jesus Christ for the remission of sins (Acts 2:38).
The patriarchal dispensation for the Gentiles ended at the cross, and with it ended the “Let your conscience be your guide” era for them. The Law of Moses for the Jews ended at the cross, and with it ended its burdensome yoke (Acts 15:10) for them.
In Christ Jesus and His new testament, circumcision is nothing and uncircumcision is nothing (1 Corinthians 7:19). Neither avails anything (Galatians 5:6). Observing all things Jesus has commanded (Matthew 28:20) does.