As Christians, we need to keep God's commandments. Jesus did not come to die for us so that we can use His blood as a license to sin. Truly believing in Jesus means to believe in Him and repent and follow Him.
Jesus says that the commandments are summed up as "Love God and love people":
"‘You shall love the Lord your God with all your heart, and with all your soul, and with all your mind.’ This is the great and foremost commandment. The second is like it, ‘You shall love your neighbor as yourself.’ On these two commandments depend the whole Law and the Prophets." (Matthew 22:37-40)
1. Do not worship other gods.
2. Do not make an idol or practice any idolatry - this includes not worshipping ancestors or angels or idolizing any human
Jesus made this commandment even stricter: "He who loves father or mother more than Me is not worthy of Me; and he who loves son or daughter more than Me is not worthy of Me. And he who does not take his cross and follow after Me is not worthy of Me. He who has found his life will lose it, and he who has lost his life for My sake will find it." (Matthew 10:37-39)
We are to love the Lord more than anyone or anything.
3. Do not take the Lord's name in vain. This means do not say "God!" or "Jesus!" when you don't mean to call on God. Do not use God's name as a curse word which many people in the world do.
4. Keep the sabbath or rest in the Lord. The New Testament does not teach us to keep a particular day (Saturday) anymore. But the Bible teaches that we are always to rest in Jesus.
Jesus said: "Come to Me, all who are weary and heavy-laden, and I will give you rest." (Matthew 11:28)
"Therefore no one is to act as your judge in regard to food or drink or in respect to a festival or a new moon or a Sabbath day— things which are a mere shadow of what is to come; but the substance belongs to Christ." (Colossians 2:16-17)
"But now that you have come to know God, or rather to be known by God, how is it that you turn back again to the weak and worthless elemental things, to which you desire to be enslaved all over again? You observe days and months and seasons and years. I fear for you, that perhaps I have labored over you in vain." (Galatians 4:9-11)
One of Satan's tactics is to get you to focus on which day of worship and forget all the other commandments of God.
Everyday is made by God. Worship God everyday. Rest in God everyday. Sabbath means rest. Let's keep the sabbath by resting in God everyday.
5. Honor your father and mother. Obey them in the Lord (Ephesians 6:1). Care for them (1 Timothy 5:4) and be patient with them when they're old (Proverbs 23:22).
6. Do not commit murder. Jesus expanded on this by saying we should not even be excessively angry with another person:
"You have heard that the ancients were told, ‘You shall not commit murder’ and ‘Whoever commits murder shall be liable to the court.’ But I say to you that everyone who is angry with his brother shall be guilty before the court; and whoever says to his brother, ‘You good-for-nothing,’ shall be guilty before the supreme court; and whoever says, ‘You fool,’ shall be guilty enough to go into the fiery hell." (Matthew 5:21-22)
7. Do not commit adultery. Jesus expanded on this by saying if we lust, it is adultery.
"You have heard that it was said, ‘You shall not commit adultery’; but I say to you that everyone who looks at a woman with lust for her has already committed adultery with her in his heart. If your right eye makes you stumble, tear it out and throw it from you; for it is better for you to lose one of the parts of your body, than for your whole body to be thrown into hell. If your right hand makes you stumble, cut it off and throw it from you; for it is better for you to lose one of the parts of your body, than for your whole body to go into hell." (Matthew 5:27-30)
8. Do not steal. This means small things and big things. This means downloading something from the internet like a song without paying for it is stealing.
9. Do not bear false witness.
10. Do not covet or desire anything that belongs to another person.
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As you can see, the ten commandments are impossible to keep on our own. But God enables us to keep them if we work diligently with Him and walk in the power of His Holy Spirit.
Some people say we don't need to keep the commandments since Jesus died for us. While it is true that keeping commandments does not bring us salvation, because no one can save himself by keeping the law. Good deeds cannot ever cancel out our failures or any bad deeds we have done. Therefore we need Jesus' blood to atone for our sins. By keeping the Law and dying for us, Jesus enabled it so that we can be perfect and forgiven through Him.
As followers of Christ, however, we need to act like we believe. That is, we cannot do lip service and sin like the devil. If we do that, then we are false believers. But a true believer who calls Jesus as Lord would do what He says.
Jesus said: "Why do you call Me, ‘Lord, Lord,’ and do not do what I say? Everyone who comes to Me and hears My words and acts on them, I will show you whom he is like: he is like a man building a house, who dug deep and laid a foundation on the rock; and when a flood occurred, the torrent burst against that house and could not shake it, because it had been well built. But the one who has heard and has not acted accordingly, is like a man who built a house on the ground without any foundation; and the torrent burst against it and immediately it collapsed, and the ruin of that house was great." (Luke 6:46-49)
So we do need to do what Jesus says, which includes following God's commandments.