They are condemned for their sins, unbelief is a sin Jn 8:24
24 I said therefore unto you, that ye shall die in your sins: for if ye believe not that I am he, ye shall die in your sins.
Notice sins plural
Sin is the result of rejecting God, trading one's own desires for the will of God. Such is more than unbelief. One can doubt which, is a form of unbelief, without actually rejecting the message. The Lord has mercy on ignorance. 1 Tim.1:13
James 1:15
Then, after desire has conceived, it gives birth to sin; and sin, when it is full-grown, gives birth to death.
Desire conceived is rejection of truth which gives rise to sin. Adam's desire to be like God is not a sin in and of itself but rejecting God's plan for life (don't eat) is what results in the eating which, is the sin. Rejection of truth is evil for it is a rejection of reality and tries to replace reality with a false reality.
Yes, we all have committed many sins but rejecting Christ is singular. No means no, as they say.