How does Christian ethics define morality?

TL;DR:

Christian ethics defines morality by the foundational call to love God fully and love others. This ethic shapes how we live, guiding our choices not by rules alone but by a heart aligned with God’s love and holiness.

what does the bible say?

An ethic is different from a law. Ethics are philosophies that underpin laws. The same ethic and many of the same laws are in both the Old and New Testaments, with some differences in how those laws are expressed. For example, Scripture indicates that believers are to be set apart. In the Old Testament, this was manifested in the civil and ceremonial laws of the Mosaic Law for the nation of Israel. In the New Testament, it is expressed as being new creations in Christ. , In both the Old and New Testaments, the command to obey God is founded on the ethic about loving God. The ethic underlying the entire Bible is loving God with all our heart, soul, and mind, and loving others as ourselves.

from the old testament

The Old Testament law about not sacrificing to idols (Exodus 20:5) is supported by the biblical ethic to worship God as holy (Deuteronomy 6:13).
Deuteronomy presents the ethic about loving God, which underlies the law about obeying God (Deuteronomy 6:1-5).
Laws about obeying parents and not cursing them (Exodus 21:17; Deuteronomy 21:18-19) are supported by the biblical ethic of honoring one’s mother and father (Exodus 20:12).
An Old and New Testament ethic is "be set apart" (Leviticus 20:26). In the Old Testament, this ethic was followed, in part, by certain dietary restrictions (Leviticus 11).

from the new testament

A Christian ethic is to consider your body a temple of the Holy Spirit (1 Corinthians 6:19), which supports the Christian law of not practicing sexual sin (1 Corinthians 6:9).
Part of spiritual growth is realizing that believers are new creations (2 Corinthians 5:17), indwelt with the Holy Spirit (1 Corinthians 12:13), and freed from the law (Romans 8:2). But we are still bound to Christian ethics, and the Bible is filled with specific ways in which we can manifest those ethics.
Whatever the law, Christian ethics can be summarized in Mark 12:29-31 to love the Lord with our whole being and to love others as ourselves.
We should be known by love for one another (John 13:35), and desire to obey God (John 14:15).

implications for today

Ethics isn’t just a class you had to take in school. It’s a philosophy that underpins laws. Christian ethics are expressed in biblical commands. In fact, Jesus expressed the Christian ethic when He said that “all the Law and the Prophets” hang on loving God and loving others (Matthew 22:37-40).

You don’t have to be a missionary or clergy to live out the Christian ethic. If you’re a Christian, you likely express a Christian ethic in myriad everyday ways: When you overlook an offense, when you talk to a co-worker about Christ, when you cook a meal for a homebound church member, when you refrain from participating in office gossip—-these are expressions of the Christian ethic.

When our hearts are bent toward loving God and loving others, our actions reflect that.

understand

Christian ethics are rooted in the command to love God and love others.
Ethics guide the purpose behind laws—not just external rules, but a heart motivation to live set apart in holiness and love, reflecting God’s character.
Living out Christian ethics happens through everyday choices, fueled by love for God and others.

reflect

How do your daily choices reflect a heart that truly loves God and others?
How are you challenged to move beyond following rules into living out God’s love through your actions and motives?
What specific area of your life might God be calling you to be more set apart for His glory?

engage

How can Christian ethics shape our understanding of morality in a culture that often defines it by personal preference?
How do the Old and New Testament expressions of being “set apart” still speak to how we live today?
How can we encourage one another to live out love-driven ethics in everyday situations like work, conflict, or service?