Dictionary.com defines "moral" as "of, pertaining to, or concerned with the principles or rules of right conduct or the distinction between right and wrong".
Whenever we look at morality in a forum such as this, it is always helpful to present what is generally known as the "Moral Argument for the Existence of God". Briefly put, if an absolute and moral God does not exist, then objective moral values do not exist. However, objective moral values do exist (in other words, some actions are morally wrong whether someone believes they are wrong or not), and therefore, an absolute and moral God also exists.
Thus, the definition of moral behavior comes directly from God, and moral behavior is nothing other than obedience to His commands.
The question, however, is why should we be moral? Why should we obey God?
The Bible teaches that we are to be moral because obedience to God glorifies He who created us, sustains us, and redeemed us. Obedience is accepted by God as worship (Romans 12:1) and is preferable to Him than sacrifice (Hosea 6:6).
In Matthew 22, when Jesus was asked what the most important of all God's commands was, He answered, "'You shall love the LORD your God with all your heart, with all your soul, and with all your mind'. This is the first and greatest command. And the second is like it: 'You shall love your neighbor as yourself'. On these two commandments hang all the Law and the Prophets."
Based on Christ's words, it has been frequently said that "love" is the greatest command.
According to the Bible, the reason Christians love is because Christ first loved us (1 John 4:19).
He demonstrated His love for us in that, while we were yet sinners, Christ died for us (Romans 5:8, John 3:16-17).
In John 14:15, Jesus tells his apostles what it means to love Him -- "If you love Me, you will keep My commandments."
In sum, we obey Christ because we love Him, and we love Him because He first loved us.
If you are like me, and have done things that are not morally right, that do not glorify God, then the Bible teaches that you deserve death (Romans 6:23). However, if you put your faith in Jesus, then He has paid the fines with His own shed blood for all of your immoral behavior (Collosians 1:19-23).
If you have not put your trust in Jesus Christ, there is no better time than now. The Bible states that if you confess with your mouth that Jesus is Lord and believe in your heart that God raised Him from the dead, you will be saved (Romans 10:9). God will then transform you, and you will then know how to truly love (1 John 4).
To be "moral" is to act with mutual concern for your own happiness and the happiness of others. You should be moral because if you aren't, you will greatly increase the risk of accumulating factors harmful to your own happiness. These factors include chronic disappointment and paranoia and hostile treatment from even a good society. But if you are moral, you will greatly reduce that risk, while increasing the opportunities to accumulate factors conducive to your happiness. These factors include good friends and personal satisfaction and joy.
Though individual acts might not reward or harm you, the effect of habitually behaving in a certain way will. It is therefore essential to cultivate the habit of moral behavior in order to manage risk and and accumulate benefits. This is a direct consequence of the fact that we are social animals who depend on a good society for our health and well being. Moreover, merely acting moral will be a chore and personally unrewarding, but actually being moral will change your life. A compassionate person, for example, will share in the joy and relief they cause in others (but feel badly if they cause unnecessary misery or anxiety), and consequently being compassionate becomes enjoyable and rewarding (while being callous or cruel becomes unenjoyable and disturbing). Likewise, honesty and reasonableness become personally rewarding when you come to truly value them and define yourself by them, so you will actually enjoy being a good person, and loathe being a bad one. By contrast, the immoral pursuit of cruelty or greed is comparatively shallow and unsatisfying. This is also a consequence of the fact that human psychology has evolved to sustain us as social animals.
A moral character is therefore essential for your own happiness. For all these reasons combined, a person who is genuinely honest and reasonable and considerate of others will have a higher probability of living a better life overall than if that same person were dishonest or unreasonable or inconsiderate of others. This has been demonstrated by the sciences of sociology and psychology. Externally, our lives work better if we work well with others, so if we are moral we will have more people willing to help us than hurt us. Internally, we loathe people who do mean and dishonest and unreasonable things to us (or to those we care about), and admire people who do kind and honest and reasonable things for us (or those we care about). Consequently we will come to loathe ourselves if we become what we loathe, and will feel good about ourselves if we become what we admire. Even if we become what we loathe but cultivate delusions to avoid confronting what we have become, the very madness that results will be debilitating, and in the end we will be increasingly paranoid and dissatisfied with everything in our lives and will persist in self-destructive behavior.
In short, life sucks if you're immoral. But if you become moral, life will be so much better and more enjoyable.
Darla the She-Goat