THE NECESSITY OF CHRIST'S SACRIFICE: To deal with the problem of sin.
Imagine a little boy who has had a good time playing in a mud puddle. When he arrives home and walks into the living room on his mother's new white carpet, she is horrified. She loves the child but not the mud. Immediately she springs into action. First, a good bath for the boy to remove the mud, then a set of clean clothes. Now he is acceptable in her living room.
Notice, the mother did not merely extract a promise from her son that he would not play in the mud anymore, then permit him to continue squishing around in his muddy shoes. Reformation is not the answer. A thorough cleansing is the minimum remedy.
God loves you! He does not love sin but he loves the sinner. Beginning with Adam and continuing through this day, every person in his natural state is contaminated with sin. Because of his love God has a plan to correct the situation and make sinners acceptable in his sight. It required that Jesus Christ give his life, shed his blood, so that sins might be washed away and even the vilest sinner may be made pure in his sight.
Sin is serious business.
The boy playing in the puddle is not particularly conscious of his muddied condition or how his mother will react when she sees him. He is busy having fun. The Bible tells us that natural man is, "...dead in trespasses and sins;".
A dead person is oblivious to circumstances around him. Natural man is not conscious of the eternal consequences of sin. Because he can enjoy sin without feeling guilty modern man tends to treat sin lightly. "So what? We all do it. We can't help it. Anyway, as long as my sin doesn't hurt anybody else what's the problem?" or, "Sin is like pepper. A little of it spices up life."
The problem with this thinking is that we are dealing with comparisons. In our own mind we consider ourselves relatively better than most of our peers. The Bible says, "But they, measuring themselves by themselves, and comparing themselves among themselves, are not wise."
2 Corinthians 10:12.
Sin is abhorrent to God.
Now try making that same comparison of yourself with God. The scale of reference has suddenly switched from relative to absolute. God is absolutely holy. God is absolutely righteous.
Since God is absolutely righteous, any disagreement with or deviation from God's will is un-righteousness -- Sin!
With regard to our little story about a child tracking mud onto his mother's carpet, imagine how the absolutely righteous God is revolted by the sight of a person soiling him/herself by rebellion and sin.
Sin is directly against God.
We tend to think of sin as minor excusable infractions; disobedient toward parents ("They do not understand."), cheating on income tax ("They are all crooks anyway."), oppressing the defenseless ("He is just a bum. So what if I burned down his cardboard box house?") and so on. The fact is, the God of the universe gave us rules in his Word, and when we commit what we consider small social sins we are in fact rebelling against God and his very serious instructions. Some general examples:
Exodus 20:1-17, Matthew 22:36-40.
Sin separates from God.
Absolutely righteous God will not tolerate unrighteousness.
God is going to prepare a permanent Heaven which will be marked by his presence. If unrighteousness will not be tolerated in his presence then people who are contaminated with unrighteousness cannot dwell there.
1 Corinthians 6:9-10.
Chapter 21 of the Revelation describes the holy city, the new Jerusalem, and ends with the statement that, "There shall in no wise enter into it any thing that defileth,...".
Atonement Atonement is satisfaction of the requirements of justice. A generation or so ago it was common to state that upon serving a prison sentence the prisoner had paid his debt to society (atoned to society) for the crime he had committed.
"...Jesus Christ, by whom we have now received the atonement."
Propitiation. A gift that secures mercy. I have heard it said that a husband who forgets his wife's birthday is prone to give her an especially nice gift the following day as an apology. Notice that in the case of God and sinful man, God, the offended, takes responsibility to provide the propitiation.
"...And sent his Son to be the propitiation for our sins."
1 John 4:10.
Justification To be justified is to be declared righteous. For example, a person whose leprosy had been healed was required to present himself to the priest to be pronounced clean.
Leviticus 14:1-7, Matthew 8:3-4.