When it comes to thinking about our sin, there are really two options.
The first is to think of our sin being externally caused. In other words, we sin because of what others have (or haven’t) done to us. We have been deprived of the love we needed. Or we have been deprived of a supporting environment. Instead, we have found ourselves in a sinful environment. Our sin is an imitation of the sin around us.
There is some truth to this. When you gather around sinners, you will be tempted to sin with them (Proverbs 1:10). But, environment isn’t the driving factor in our sin. Rather, environment helps to bring out what’s already within us.
The second way to think about our sun is to look within. Fundamentally, we sin because of something within us. In other words, we sin because we are depraved beings. Our environment will induce our sinful hearts to do what they want to do. We are depraved beings, not deprived beings. Jesus said, “That which proceeds out of the man, that is what defiles the man” (Mark 7:20).
This is why we need our hearts transformed, rather than mere moral improvement. Our hearts are bad. We are depraved. This is why the New Covenant included promises like the following: “I will give you a new heart and put a new spirit within you; and I will remove the heart of stone from your flesh and give you a heart of flesh. I will put My Spirit within you and cause you to walk in My statutes, and you will be careful to observe My ordinances” (Ezekiel 36:26-27).