"Therefore, since we have been justified through faith, we have peace with God through our Lord Jesus Christ, through whom we have gained access by faith into this grace in which we now stand."
This verse can only be understood in the light of the pre-condition of having "peace with God through our Lord Jesus Christ". That pre-condition is a "warring" relationship.
B.C. or Before Christ reigns in our hearts and minds - Romans 5:6 calls us "powerless" and "ungodly". Romans 5:8 calls us "sinners". Romans 5:9 calls us condemned to "God's wrath". Romans 5:10 calls us God's enemies.
"You see, at just the right time, when we were still powerless, Christ died for the ungodly. Very rarely will anyone die for a righteous man, though for a good man someone might possibly dare to die. But God demonstrates his own love for us in this: While we were still sinners, Christ died for us."
"For God so loved the world that he gave his one and only Son, that whoever believes in him shall not perish but have eternal life." (John 3:16)
I once saw a bumper sticker that said it really well....
No Jesus, No Peace
Know Jesus, Know Peace
And that my friends is God's Truth! Thank you Lord for your Salvation and your Peace! Amen!