I believe the contrast is the death sin produces and the life that is in Christ.
Another good example is the mind set on the flesh, which is death, and the mind set on the Spirit which is life in Christ.
The contrast is the product of sin (death, as sin begats death) and the gift of God (which is life).
It is not a versus situation. It is physical death and then the gift of God (Christ). Those who remain in their sins, who ate condemned, are so because they reject this Gift (the condemnation os this, that the Light came into the world and men rejected the Light because their deeds were evil).
I see the verse (Romans 6:23) not as a contrast but a truth statement.
I disagree....maybe?. Or I might agree....I'm really not sure.
You decide:
Physical death is the result of sin. The second death is God's judgment against the wicked.
If we use "spiritual death" to be the opposite of "spiritual life" then spiritual death is a mind set on the flesh. This produces sin, which produces death. Then there is spiritual life (Christ in is).
The issue I have is with those who believe Adam was "spiritually alive" and essentially killed God (killed or died to Christ in Him....i.e., Life).
It redefines too much.
Spiritual life is eternal. Being dead in our trespasses is not eternal (for those saved) as they are given spiritual life.
But if we are talking about the second death as being "spiritual death", then that is everlasting.
We approach it differently and will see it differently.
What stands out to me in the verse is the spiritual death (separation from God) through sin.
But God made a way for us to escape it.