how can sin have spiritual consequences?

In the most basic sense (and literally), sin means "missing the mark." Most modern church teaching defines sin as anything that Jesus wouldn't do; any thoughts/actions that fall short of his nature.

Assuming a comparable definition to this one, how does sin affect the spiritual realm? Most of the things we associate with sinfulness have no significance outside the physical world...

To use an example- sexual sin. Since gender and sexuality are biological functions created for reproduction, what significance could their use or misuse have outside of this world?

Obviously God's law (especially going back to Mosaic law) is intended to guide as toward making good choices that improve our lives and the lives of those around us- but how do bad choices separate us from God in an eternal, spiritual sense? (Other than separating us from the joy righteousness brings us in this life)

Your thoughts?

You have a misunderstanding in your definition of 'sin' which is leading you down the road of gnosticism.

Sin is not a physical thing...it is not necessarily a mark which we fail to live up to, but more of a failure to love and honor God in our heart. The heart is where sin is created. Jesus addressed this when he was talking to the Pharisees about rituals and traditons. It is not the outward acts that make a person sinful...it is their heart- a heart that is selfish and prideful, not concerned about anything or anyone else at that moment.

Sin is a big deal to God, because it is the only thing that can separate us from him-spiritually. It breaks the relationship, the trust, and the fellowship between us and God. Only God can fix this...and he does through Jesus-a pretty big price just to have a good relationship with someone...

I understand your position on the importance of our hearts, but this too leads to more questions. If a person acts with pure intention in an attempt to live a life that pleases God, does that make him sinless (regardless of what his actions are)?

This seems like an interpretation more in line with the message of grace, but it seems to contradic mainstream church teaching as well. I'm still not hearing the reason as to how sin takes on spiritual power...

No. Unless he never acts out of selfishness or pride. I doubt that any of us can admit this. How can you 'sin' with a pure intention?

Let me re-state this another way: Sin spiritually separates us from a sinless, Holy God. When you sin, you are no longer in fellowship with God, because he cannot participate in sin. IT is spiritual, not physical. A physical act, such as murder, is sin because you are spiritually corrupt in your heart- you are taking away someone else's life. This is wrong.

THE DIFFERENCE is in that sometimes killing is not wrong. When you kill accidentally (like a car accident), you were not intending to take someone's life. You didn't even know the person..it was not a sin to kill this person because instead of hatred, you rather have compassion and sadness.

The same action, yet one is a sin, the other is not. The difference? Motives of the heart.