Those righteous of the Old Testament still waited for the day Jesus came and died for the world.
No one was made perfect until Jesus came and died.
Faith in Jesus' blood makes those belonging to God perfect, even those who died before Jesus’ ministry on earth; however, they still had to wait till Jesus' blood was shed. The Old Testament righteous people who died before Jesus came to earth, they did not in their time get to see the promised salvation through Jesus Christ, the grace that was to come (1 Peter 1:10-12; 2 Peter 1:19; Romans 16:25-26; 1 Corinthians 4:1).
Paul says about the faithful in the Old Testament times, "These were all commended for their faith, yet none of them received what had been promised. God had planned something better for us so that only together with us would they be made perfect."
God's grace through faith in Jesus made the spirits of the righteous, those who had died before Jesus, they in the spirit were made perfect together with Paul and the other first Christians (Hebrews 12:23; 11:39-40).
The Old Testament faithful were alive in the spirit watching from above. Paul says, "Therefore, since we are surrounded by such a great cloud of witnesses..." Jesus also tells us Abraham waited to see his day, Abraham saw it and was glad (John 8:56). Abraham died, yet was alive in the spirit.
There were those who disobeyed and died before Jesus came to earth, though they were dead their spirits went to a prison, unlike the spirits of the righteous.
After Jesus was crucified, he preached to those who were dead, he preached to the spirits in prison, the spirits of those who had died and disobeyed long ago (see 1 Peter 3:18-19). Those people who disobeyed and died before learning of Jesus...Jesus preached the gospel to them, so that they might be judged according to men in regard to the body, but live according to God in regard to the spirit (1 Peter 4:5-6). For Christ died for sins once for all, the righteous for the unrighteous, to bring us to God, even those who lived and died before Jesus.
THAT is SCRIPTURE. That is the WORD OF GOD. Jesus died FOR ALL. That includes the people who DIED BEFORE HE CAME.
Jesus came to earth and taught those on earth. Then Jesus descended to the spirits in prison to preach to them, to those who disobeyed long ago. Jesus then ascended higher than all the heavens. Jesus filled the whole universe (see Ephesians 4:10).
These scriptures show we have living, thinking spirits that live on after the death of the body. Some spirits go with those who disobey, and spirits of the righteous live in heaven. These scriptures show that our spirits live on, and how Jesus filled the whole universe.
Rejoice at Jesus saving us, and rejoice at knowing without a doubt that the Word of God tells us we have spirits that live on.