Sin Scales

I've been thinking a lot lately about sin.  It's a very complicated subject because what is considered a sin can vary from one religion to another, one family to another and even one person to another.  Some people think drinking alcohol is a sin, others (myself included) believe that it is only when you drink alcohol in excess that you have sinned.  God gave us some rules in the Bible.  The Ten Commandments are probably rules everyone (at least Christians) can agree on.  But even if we all agreed what is and isn't a sin, it's still really complicated.

If something is a sin, does that mean it is always a sin, no matter the circumstances?  For example, if someone broke into my house and tried to kill me but I killed them first, have I sinned?  One of the Ten Commandments is "Thou shalt not kill".  Before I go any further, let me say that I fully believe God forgives us for any and all sins that we ask Him to forgive.  He has mercy and grace that none of us can comprehend and there's nothing we can do that He can't forgive us for.  His forgiveness is not what I'm talking about here.  Acts 2:38 says:

"Peter replied, "Repent and be baptized, every one of you, in the name of Jesus Christ for the forgiveness of your sins. And you will receive the gift of the Holy Spirit. "

That word repent says to me that we must acknowledge the fact that we have sinned in order to be forgiven.  So back to my example.  When I kill someone in self-defense, have I sinned.  I think the answer is probably yes.  Does that mean I should feel guilty for protecting myself?  I don't think so, I think it means that I should feel sad that I was forced to kill someone.  I think it means I should go to God and tell him that I'm sorry that I took a life.  And then I'll be forgiven. 

There's also the difference between law and sin.  It's not against the law to commit adultery, but it is a sin.  It's not a sin to drive over the speed limit but it is against the law.

And then there's the complication that I have been struggling with and the reason for this post.
 
Are some sins worse than others? 
 
Here's my dilemma, if God can forgive all of our sins just by us asking for forgiveness, then doesn't that mean that in His mind all sins are the same?  Is He sitting up there with a set of scales and giving forgiveness out according to the weight of the sin?  I just can't see that in my mind. 
 
I know that I can never hope to understand His ways, but the way I see it (from my human mind) is that God gave us the Bible and in it He explicitly told us not to do certain things.  There are no "excepts" in the Ten Commandments.  It doesn't say thou shalt not kill except if someone is trying to kill you.  It's very straightforward.  But it seems like in every day life we weigh sins.  One of the commandments is "Thou shalt not lie".  But how many of us can honestly say we don't lie?  Is it a sin to lie to my husband when he asks me what I bought him for Christmas?  I think most people would say no.  I wouldn't immediately think this is a sin myself.  But put it in a different situation.  Maybe my husband is asking me what I bought him because he is worried about our financial situation and I have a habit of buying him things that are above our means.  (For the two mothers that I know read this, I just want to say this is not real, just hypothetical :) )  If I tell him I spent nothing but actually spent several thousands of dollars above what we can afford, is the lie a sin? 
 
I think there is a danger is weighing our sins.  Because I don't think God weighs them.  I think that He hates sin.  I don't think He hates us for sinning, but I do think He hates sin.  In my mind I imagine Him feeling hurt every time one of us sins. 

My own Church weighs sin.  We call them mortal/grave and venial sins (venial being the smaller, not as bad sins).  But I've always been told that even mortal sins are forgiven if we simply ask for forgiveness.  So is there really any difference to God?

I guess the brunt of my struggle is that I want to be a good Christian.  I want to be a good Catholic.  I want to love God with every part of my being and I want to be the kind of person that people see and know that God is part of my life.  I want to be like Jesus.  But every single day I fail in some way.  And then I find myself rationalizing to myself or to others, attempting to justify my sins.  Even if they are just "little" sins, if we KNOW what we are doing is wrong (that it is a sin), isn't it just as bad as committing a "big" sin?  If we KNOW we are going to hurt God, isn't that grave?

And now we're back to what is and isn't sin.  In parts of the Bible it says not to eat any pork.  Does that mean that eating a pork roast or pork chop is a sin?  I honestly don't think so, but what gives me the right to say that?  Most, if not all, Christians believe God gave us the Bible and if it did come from Him, how can we question it?  And if the Bible is wrong, who has the power to say it is and to then tell us what is right or wrong?  Also, should we attempt to interpret what is written in the Bible (including things that aren't mentioned or excluding things that are), or take it at face value? 

I don't have the answers.  It would be great if God could just post a little comment and lay it out for me.  But I doubt that's going to happen.  However, I am open to any input!