Sin is an Attitude
Sin is far more than just breaking God's Laws. It's an attitude.
It's like saying "stuff you, I know what's best" to God who is our Father.
That kind of attitude gets worse and worse, until it becomes a full-on rebellion worthy of death.
But every man is tempted, when he is drawn away of his own lust, and enticed. Then when lust hath conceived, it bringeth forth sin: and sin, when it is finished, bringeth forth death. Do not err, my beloved brethren.
- James 1:14-16 (KJV)
God's Law (the Ten Commandments) is non-negotiable, and we ought to obey God 100% all the time.
God's Law is actually good for all of us, and not a burden at all.
Come unto me, all ye that labour and are heavy laden, and I will give you rest. Take my yoke upon you, and learn of me; for I am meek and lowly in heart: and ye shall find rest unto your souls. For my yoke is easy, and my burden is light.
- Matthew 11:28-30 (KJV)