I've just got back from my youth group after having a discussion about living together before getting married. I've search your articles and I don't think they quite answer the question "Is living together before marriage a sin?" We actually want to know is living together, but not sleeping together, before getting married a sin -- just simply living together! Do you know of any Bible verses that I can come back at them as they all see to have the opinion that it's all good!
One of the problems with sin is that it is deceptive. "Let no one say when he is tempted, "I am tempted by God"; for God cannot be tempted by evil, nor does He Himself tempt anyone. But each one is tempted when he is drawn away by his own desires and enticed. Then, when desire has conceived, it gives birth to sin; and sin, when it is full-grown, brings forth death. Do not be deceived, my beloved brethren" (James 1:13-16). It doesn't come all at once with horns blaring and red flags waving. It creeps up a bit at a time. At each small step it looks like the next step isn't so bad and definitely no worse that the prior step. That is why Paul warned "Test all things; hold fast what is good. Abstain from every form of evil" (I Thessalonians 5:21-22).
Young people are filled with good intentions, but they are notorious for not being able to assess risk accurately and consistently. It is not putting youth down, it is just a fact of life that during the years of growing up, the brain develops as well. One of the last things to mature is the section which deals with judgment. The question should be asked, "What do you think will eventually happen when two people of the opposite sex, who like each other, spend a lot of time together with no one seeing what they do?" What ends up happening is that as the people get more comfortable with each other, liberties are taken. It doesn't happen all at once, but eventually things go further than intended.
I'm talking with one girl right now in just this situation. It started with her rooming with her boyfriend's sister and he coming to visit on the weekends. Over a period of time, it moved from there to his sleeping in her bed -- but no sex. Then it became sexual touching. Then one night it was actual sex. She's upset because that wasn't her intention. Yet she could not see that this was the inevitable destination of the road she started to walk.
Now, let's assume that you just met Joe and Sally and you learned that they are living together in the same apartment; what would you honestly assume? A reason people of the opposite live together -- for the vast majority -- is to have opportunities to have sex, so it would be a natural conclusion. Thus, let's assume that two people actually do live together, but don't share a bed. What kind of example will they be giving to others? Paul once was collecting money to send to needy people in Jerusalem. But when it came time to pick up the money, he insisted that the churches select someone to carry the money. Of all the people I would trust on delivering money to where it should go, Paul would be high on my list. But Paul want to make sure there wasn't any appearance of wrong doing. They were "providing honorable things, not only in the sight of the Lord, but also in the sight of men" (II Corinthians 8:21). God knew he would not pocket the money, but Paul wanted people to be confident about it as well.
Even if two people could live together and avoid having sex together, their example would encourage others to try it -- others who are likely not to have the same strength of will as they do. Thought they may manage to avoid sin, their example would be an encouragement to others who then end up sinning. "Let no one despise your youth, but be an example to the believers in word, in conduct, in love, in spirit, in faith, in purity" (I Timothy 4:12). Would you want to arrive at Judgment and have God point out that because of your example others fell into sin?
The real problem is that people aren't shunning sin. They find it fascinating. They try to see how close they can get to the line without actually stepping across. We should be serious about the horror of sin. We ought to be trying to get as far from it as we can get. "Therefore we also, since we are surrounded by so great a cloud of witnesses, let us lay aside every weight, and the sin which so easily ensnares us, and let us run with endurance the race that is set before us" (Hebrews 12:1).