Be careful to live properly among your unbelieving neighbors. Then even if they accuse you of doing wrong, they will see your honorable behavior, and they will give honor to God when he judges the world~ 1st Peter 2:12 NLT
Heresy is a just a fancy-pants theological term for the act of departing from a pattern of sound biblical teaching (1st Timothy 6:20-21, 2nd Timothy 1:13, 2nd Timothy 4:3).
Sometimes heresy takes the form of some seriously insane theories about God.
There were once Christians who believed that Jesus was simply a human being who was formally adopted by God at his conception. Once the adoption was “finalized” he developed a divine (God) nature while growing in Mary’s womb (Adoptionism). Other early believers were convinced Jesus was a phantom who didn’t leave footprints when He walked rather than a flesh and blood person (Gnosticism). For nearly a thousand years some “Christians” believed people are born without a sin nature and are capable of living a holy life apart from Jesus and the regeneration of the Holy Spirit (Pelagianism).
Most heresies are not wholesale lies about God or crazy misinterpretations of Scripture. Most heresies are more like tiny kernels of truth wrapped-up in half-truths and weird errors. There are two such heresies deeply rooted in our contemporary Christian culture. The first is legalism. Legalists believe they can earn God’s favor by doing the right things and obeying the right rules.
It is true that God really cares about our behavior (more on that later). However, legalists would do well to remember that even the best-behaved person in the world cannot save themselves from their own sin (Ephesians 2:8, 2nd Timothy 1:9, Hebrews 10:39). Legalism sidetracks Christians from relationship with Christ by placing the emphasis on what we can do for ourselves rather on what Jesus did for us. Perhaps, the biggest drawback to legalism is that it falsely paints God as demanding, callous and impossible to please. This can lead legalists to feel discouraged and resentful towards God. This can lead to hopelessness and eventually even a departure from the faith.
On the other end of the doctrinal spectrum are those who believe there are no rules and that behavior is a nonissue for Christians. These folks think that once a person is saved there is nothing they can do or not do to offend God. Christians who have intentionally or unintentionally adopted this view do not worry seriously about the effects sin, even deliberate, premeditated sin. Adherents to this view are growing in number and having an enormous impact on the Christian culture.
The truth is that our behavior does matter but not because it saves us, or makes God like us more. Correct behavior and following the rules matter for four reasons:
Righteous behavior protects us from moral failure-
Ephesians 6:14 instructs Christians in a metaphorical sense to put on the “breastplate of righteousness”. The primary purpose of a breastplate in Roman body armor was to protect the soldier’s heart from injury. In Proverbs 4:23 the writer instructs readers to “guard your heart because everything you do flows from it”. Behaving in a way that is righteous (avoiding sin and questionable behavior) protects us from all sorts of pitfalls and potential disasters. For example, going out of your way to avoid pornography protects against addiction, the sin of lust and at least a dozen other really ugly sins. Avoiding people who gossip ensures that you will not become a slanderer (Psalm 15:1-3) and if you never drink alcohol you will never become an alcoholic.
When Christians behave virtuously non-Christians have the opportunity to experience something the Bible calls conviction-
Perhaps the most critical reason to avoid sin and to behave righteously is because when we do the people around us have a model of good behavior to follow. Sometimes our good behavior even leads sinners to feel guilt or conviction over their bad behavior (1st Peter 3:13-16). Conviction often leads to repentance.
Christians are commanded to avoid certain behaviors and sins-
The New Testament gives a series of “sin lists” addressed to Christians (Mark 7:21-22, 1st Corinthians 5:10-11, 1st Corinthians 6:9-11, 1st Timothy 1:8-11, Colossians 3:5-8, Galatians 5:19-21). Most of those lists are predicated with or followed by the caution that people who routinely practice the sins listed will not “inherit the kingdom of God”. In my view it is reasonable to question the salvation of any “Christian” who does not take these warnings to heart.
Bad behavior causes Christians to lose their moral authority-
There was a time in the not-so-distant past when most people (saved or unsaved) looked to the church for moral direction and spiritual guidance. However, allegations of fraud, sex abuse scandals, infidelity and wholesale hypocrisy amongst clergy and laypeople alike have stripped the church and the people in it of any moral authority they were once blessed with. Now our culture is swimming in moral chaos and thanks to the sinful antics of Christians over the last forty years no one is looking to the one source that truly has the answers to our problems: the church.
God loves people so much that He sent His Son, Jesus, to save people from their sin (John 3:16). His love doesn’t end there though. God also loved us enough to give us moral boundaries to keep us from going off the rails after we come to know Jesus. It’s up to us to stay within those boundaries.