When we read the Bible, how do we know what we have to do to be saved depending on what part of the scriptures we read? Is it the Law, is it Faith and the law? Is it Faith alone?
In the beginning, God gave only one commandment to Adam to not eat from the tree otherwise he would die spiritually (Genesis 2-3). He died by disobedience and all humanity is spiritually dead as Adam’s descendants.
Abraham believed in God’s promise in Genesis 15 to be righteous by faith and not works.
God then commanded circumcision to Abraham and his descendants to enter the old covenant (Genesis 17, Galatians 3)
God commanded the 10 commandments and 603 ordinances to Israel to remain in the old covenant (law of Moses, or the Law)
Jesus was born under the old covenant to preach the fulfillment of the law to Israel (Galatian 4:4, Matthew 5:1-48, Luke 12, Luke 14, Matthew 6-7, Matthew 19). He told them how to truly fulfill the law by being sinless, perfect in their heart, word, deed and being perfect like God in following Jesus, selling everything and carrying the cross, dying as martyrs.
But nobody fulfilled the law except Jesus.
The law could not save anyone and therefore Jesus died on the cross to end the law so that righteousness is given to all who believe (Roman 10:4)
In the last generation of the law (40 years from the Cross till AD70), they had to obey 2 commandments: Believe in Jesus and love one another to fulfill the law.
The law fully disappeared in AD70 when the temple was destroyed.
Today the law does not exist. Sin does not exist because Jesus took away the law by His death on the cross. He forgave all our sins. The world is forgiven. The barrier between God and man has been taken away. Where there is no law, there is no sin (Romans 4:15)
Now God calls people to receive eternal life by faith in Jesus.
The ONLY commandment is to believe in Jesus to take the free gift of life (Revelation 22:17)
Everyone who believes in Jesus receives the forgiveness of sins.