What does the Bible say about Christian behavior?

TL;DR:

Believers are called to live out their new identity in Christ by obeying God’s Word and demonstrating the fruits of the Spirit through love, service, and godly behavior. Though imperfect, our ongoing transformation shows God’s work in us and serves as a witness to others.

what does the bible say?

When we become believers, our lives are permanently changed, and our actions should exemplify our new identity in Christ. One of the most important actions we should take is extending Christ-centered love toward everyone, which can look like pursuing peace, sacrifice, service, and so on for people who don’t “deserve” it from us. We can also pursue godly actions through expressing zealousness for the gospel, evidencing the fruits of the Holy Spirit, and conforming to God’s will through obeying His Holy Word. It is humbling to also realize our need to take action when we sin against God. In such situations we should confess our sin to Him. Living out our faith through obedience to God’s Word helps avoid us being swayed by our flesh and it helps us be a witness to God’s transformative work in our life.

from the old testament

The Old Testament doesn’t specifically address “Christian behavior” since it was written before Christ’s coming, but it does lay the foundation for godly living through commandments, laws, and wisdom that shape how God’s people should live. Principles like loving God and others (e.g., Deuteronomy 6:5; Leviticus 19:18), pursuing justice, mercy, humility (Micah 6:8), and obedience to God’s commands all point toward the kind of holy, righteous life that Christians are called to continue and fulfill in the New Testament.

from the new testament

As Christians, we should not be ashamed of our witness for Christ: "For I am not ashamed of the gospel, for it is the power of God for salvation to everyone who believes" (Romans 1:16). Bolding living our faith is an action we must take as a believer.
When we become Christians, the Holy Spirit indwells us and empowers us to walk with God, displaying godly behavior in our daily lives (Romans 8:9).
A Christian’s behavior should be distinguished by genuine love and goodness, such as showing honor to others, serving the Lord with zealousness, rejoicing in hope, being patient during tribulation, and being constant in prayer (Romans 12:9-12).
Blessing others is a big part of Christian behavior, too. We are to serve the needs of fellow believers, seek to extend hospitality, bless those that persecute us, “rejoice with those who rejoice” and “weep with those who weep,” as well as “live in harmony with one another” (Romans 12:13-16).
We are called to seek peace and care for others, too. We should “associate with the lowly,” “repay no one evil for evil,” but rather “do what is honorable in the sight of all” (Romans 12:16-17). As we seek to live in peace with everyone, we should love our enemies and care for those in need; instead of being overcome by evil, we must “overcome evil with good” (Romans 12:18-21).
We can’t do good works apart from the Holy Spirit empowering us; it is His work of transformation in our lives that deserves the credit (2 Corinthians 3:18; 5:17).
A foundational passage on Christian behavior is Galatians 5:22–23, which lists the fruit of the Spirit: "But the fruit of the Spirit is love, joy, peace, patience, kindness, goodness, faithfulness, gentleness, self-control." Our life should be characterized by these attributes.
Christians are told to obey God and conform to His will. Philippians 2:12–13 says it this way: "Therefore, my beloved, as you have always obeyed, so now, not only as in my presence but much more in my absence, work out your own salvation with fear and trembling, for it is God who works in you, both to will and to work for his good pleasure."
Being a Christian means that we have been adopted as sons and daughters of God. First Peter 2:9–10 says: "But you are a chosen race, a royal priesthood, a holy nation, a people for his own possession, that you may proclaim the excellencies of him who called you out of darkness into his marvelous light. Once you were not a people, but now you are God's people; once you had not received mercy, but now you have received mercy." As God’s children, we should behave like His Son—living our lives out in a Christ-like manner.
Walking out Christian behavior displays God in us to others, but it also aids us in our battle against our fleshly desires: "abstain from the passions of the flesh, which wage war against your soul" (1 Peter 2:11).
An important action we should take as Christians is confessing our sin and moving forward as we trust in God's grace and faithfulness (1 John 1:9).

implications for today

As Christians, our lives should display salvation and the changes that God has worked within us (John 15:8). Practically speaking, this looks like applying God’s word to our life—sharing the gospel, caring for others, living out the fruits of the Holy Spirit—all in Christ-like love. However, we must recognize that the Holy Spirit's work in us is progressive. We will mess up, and our behavior will not always adhere to God's holy standards or be a very good demonstration of His work in us. However, when we fail, we can trust that "we have an advocate with the Father, Jesus Christ the righteous" (1 John 2:1). Ultimately, we must not be inactive participants in our Christian walk but doers of the word who evidence our faith through our actions (James 1:22, 27; 2:17, 26).

understand

As believers, our identity in Christ calls us to live out godly behavior.
Christian behavior is empowered and transformed by the Holy Spirit.
Though imperfect, our ongoing obedience and confession of sin demonstrate God’s work in us and serve as a powerful witness to the world.

reflect

In what specific ways is your daily behavior reflecting your new identity in Christ and the fruit of the Spirit?
How do you respond when you recognize sin in your life—are you quick to confess and rely on God’s grace to transform you?
Where do you struggle most to demonstrate Christ-like love, patience, or humility, and how can you invite the Holy Spirit to empower you in those areas?

engage

How do we see the connection between Old Testament principles of how God called the Israelites to live and the New Testament call to live out Christian behavior today?
What are some practical ways we can support one another in embodying the fruit of the Spirit in our community and daily lives?
How does understanding that Christian behavior is an ongoing process shaped by the Holy Spirit change the way we encourage and hold each other accountable?