The word gospel literally means good news. However, good news is very different from good advice. Good advice is something we need to do, but good news is a declaration of something that has already been done.
The gospel is that God himself has come to rescue and renew all of creation in and through the work of Jesus Christ on our behalf. So why does creation (which includes you and me) need rescuing? The answer is sin. In order to understand the good news we first have to understand the bad news. Paul David Tripp describes sin like this:
“Sin is the ultimate disease, the grand psychosis. You cannot escape it or defeat it on your own… Our deepest problem is not experiential, biological, or relational; it is moral, and it alters everything. It distorts our identity, alters our perspective, details our behavior, and kidnaps our hope.”
See, before sin ever becomes an action, it is a condition. The problem is not merely external, but internal. Our behaviors are determined by our emotions. Our emotions are determined by our thoughts. And our thought sare determined by our desires. The book of James says it like this:
13 Let no one say when he is tempted, “I am being tempted by God,” for God cannot be tempted with evil, and he himself tempts no one.14 But each person is tempted when he is lured and enticed by his own desire.15 Then desire when it has conceived gives birth to sin, and sin when it is fully grown brings forth death. James 1:13-15 ESV
People usually try to blame their sin on their circumstances (I got angry because someone cut me off in traffic, I started to worry because I lost my job and my finances are low, I yelled at my roommate because they weren’t listening to me). However, the reality is that our circumstances are not the cause of our sin, but merely serve to reveal what is already in our hearts. Everything we say and do is rooted in what we desire, and what we desire is rooted in what we believe. The author of Hebrews says this:
12 Take care, brothers, lest there be in any of you an evil, unbelieving heart, leading you to fall away from the living God. Hebrews 3:12 ESV
Another way it could be said is like this:
“Sinful acts always have their origin in some form of unbelief; behind every sin is a lie. The root of all of our behaviors and emotions is the heart, what it trusts and what it treasures.” -Tim Chester
Sin is never truly conquered by simply changing our outward behaviors, what really needs to change is what we are believing in our hearts. All sin is a heart issue, and the gospel is the only message that has the power to change the human heart. In light of this, all sin is ultimately a gospel issue.
16 For I am not ashamed of the gospel, for it is the power of God for salvation to everyone who believes, to the Jew first and also to the Greek. Romans 1:16 ESV