I agree, we are no longer flesh but spirit. So th flesh has no more power over us, But it is still there, We still have to realise that it can come when we are not expecting it, and boom, We wonder why we just commited that sin. We can not go around thinking it is dead so we no longer have to worry about it.
Romans 8 is our power. But how many of us do romans 8 24/7? I know i do not.. I try, but every night, if I think of my day, I am reminded of the times I did not focus on the spirit, but I was self (flesh) focused, and and I realise in those times, I was in danger and succeptable to committing a sin or two. And in reality, I was in sin to begin with because i was focused and serving self. Not God.