I absolutely believe that we need to speak the Word only so that it will come to pass in our lives--it's a spiritual principal, a supernatural law; but that doesn't negate the effect of sin in our lives.
Well, let's look at a couple things.
First, I agree in concept with what you've said and agree that it is easier to teach the "effect of sin in our lives."
So, obviously we have two things to consider:
(1) Sin as it relates to salvation.
Romans 4:8 (NET)
blessed is the one against whom the Lord will never count sin."
When we are saved God forgives ALL of our sins. Salvifically they are removed forever. This is why we read:
1 John 3:9 (NET)
Everyone who has been fathered by God does not practice sin, because God's seed resides in him, and thus he is not able to sin, because he has been fathered by God.
How can it be said that we are not able to sin when we know we sin daily?
This is because God doesn't recognize our sin any longer. We are seen through Jesus' Blood. We are washed in the Blood. We are imputed the righteousness if Jesus.
Psalms 103:12 (CEB)
As far as east is from west
thats how far God has removed our sin from us.
As far as God is concerned, our sins are removed. Gone.
So that brings up....
(2) Sin as it relates to sanctification.
This is where Romans comes in. Chapter 7:14
Romans 7:14-20 (NET)
14 For we know that the law is spiritual - but I am unspiritual, sold into slavery to sin. 15 For I don't understand what I am doing. For I do not do what I want - instead, I do what I hate. 16 But if I do what I don't want, I agree that the law is good. 17 But now it is no longer me doing it, but sin that lives in me. 18 For I know that nothing good lives in me, that is, in my flesh. For I want to do the good, but I cannot do it. 19 For I do not do the good I want, but I do the very evil I do not want! 20 Now if I do what I do not want, it is no longer me doing it but sin that lives in me.
There is a separation of our new man, our spirit man, from our old man, our carnal man. 1 John 3:9 refers to our new man. Our spirit is new, pure, sinless. But when we transgress God's commands it is sin in us, our old man, that is doing this.
Now our soulish man has a choice: follow the spirit man or the carnal man. This is where sanctification plays its part. God won't force our answer here, but He will guide through His Holy Spirit to convict us toward righteousness.
Romans 6:6-14 (NET)
6 We know that our old man was crucified with him so that the body of sin would no longer dominate us, so that we would no longer be enslaved to sin. 7 (For someone who has died has been freed from sin.) 8 Now if we died with Christ, we believe that we will also live with him. 9 We know that since Christ has been raised from the dead, he is never going to die again; death no longer has mastery 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 too consider yourselves dead to sin, but alive to God in Christ Jesus. 12 Therefore do not let sin reign in your mortal body so that you obey its desires, 13 and do not present your members to sin as instruments to be used for unrighteousness, but present yourselves to God as those who are alive from the dead and your members to God as instruments to be used for righteousness. 14 For sin will have no mastery over you, because you are not under law but under grace.
So, sanctification. Notice in the bold: :do not present your members to sin". You are anew man, sinless. Your carnal self still is enticed by sin. Your soulish man, under sanctification, needs to learn to choose: spirit or carnal; blessing or curse; life or death.
Your sin is not salvific, but rather it affects you walk. God protects you once your sins are forgiven.
1 John 5:18 (NET)
We know that everyone fathered by God does not sin, but God protects the one he has fathered, and the evil one cannot touch him.
But the devil is the accuser of old. He s a liar, a deceiver, and he is out to steal, kill and destroy whatever he can of your blessing. You see in 1 John 5 above that he can't touch you salvifically.
What he does is lie to us. He makes us ponder sin. He convinces us to step outside the hedge of protection. He gets us to step into the curse.
When we do this we become double-minded in many ways.
At times we attempt to justify our sin. "That's not so bad." "That's just a 'little' sin." We attempt to have fun with our sin.
At other times we recognize our sin and it shames us. We withdrawal instead of falling before God for help. Understand, He's already done away with the very sin we are ashamed of. So what are we ashamed of?
Ultimately, our position makes us doubt that we are worthy to approach God, to ask for something, to think that we are worthy enough to receive. It is our double-mindedness that truly gets in our way.
Sure, the root cause is our sin. But sin didn't stop God: He already forgave us and views us as a child who cannot sin (1 John 3:9). But He expects, through our sanctification, that we will strive for confidence in Him and His promises.
James 1:6-8 (NET)
6 But he must ask in faith without doubting, for the one who doubts is like a wave of the sea, blown and tossed around by the wind. 7 For that person must not suppose that he will receive anything from the Lord, 8 since he is a double-minded individual, unstable in all his ways.
When we embrace the sin in us (remember, Paul says our transgression is not us, but sin in us -- our old man) and allow it to take us out of the blessing we are affected. We become double-minded. And it is this lack of confidence in God's will for us that hinders our results.
Remember:
1 John 5:14-15 (NET)
14 And this is the confidence that we have before him: that whenever we ask anything according to his will, he hears us. 15 And if we know that he hears us in regard to whatever we ask, then we know that we have the requests that we have asked from him.
According to His will. We know this to be according to His Word, His promises. But it also is our confidence. For that is according to His will as well.