Additionally, the concept of union with Christ affects the teaching of limited atonement.
It is only those who are joined to Christ that participate in his death and resurrection.
Unbelievers are never joined to Christ.
I doubt half of free-willers even understand the concept of union with Christ, so I am probably wasting my time explaining this, but the Christian teaching is that believers are united with Christ through faith, and thus participate in his death and resurrection. They die to sin, and they are resurrected to righteousness and newness of life.
They do this through being associated with HIS death, burial and resurrection.
An unbeliever is never associated with his death, burial and resurrection. It is only believers who are associated with it.
Like I said, though, at the shallow, Sunday school, traditionalist, religionist level of understanding, this probably won't even make sense. i suggest reading the book Union with Christ by Rankin Wilbourne in this regard. It doesn't talk about limited atonement, but the concept definitely applies.
The unbeliever never experiences this union, so they don't participate in his crucifixion, death, burial or resurrection. Therefore, atonement of the Cross doesn't apply to them.
Romans 6:1-14 1 What shall we say then? Are we to continue in sin that grace may abound? 2 By no means! How can we who died to sin still live in it? 3 Do you not know that all of us who have been baptized into Christ Jesus were baptized into his death? 4 We were buried therefore with him by baptism into death, in order that, just as Christ was raised from the dead by the glory of the Father, we too might walk in newness of life.
5 For if we have been united with him in a death like his, we shall certainly be united with him in a resurrection like his. 6 We know that our old self was crucified with him in order that the body of sin might be brought to nothing, so that we would no longer be enslaved to sin. 7 For one who has died has been set free from sin. 8 Now if we have died with Christ, we believe that we will also live with him. 9 We know that Christ, being raised from the dead, will never die again; death no longer has dominion over him. 10 For the death he died he died to sin, once for all, but the life he lives he lives to God. 11 So you also must consider yourselves dead to sin and alive to God in Christ Jesus.
12 Let not sin therefore reign in your mortal body, to make you obey its passions. 13 Do not present your members to sin as instruments for unrighteousness, but present yourselves to God as those who have been brought from death to life, and your members to God as instruments for righteousness. 14 For sin will have no dominion over you, since you are not under law but under grace.