The only way to answer such a question is to look at the Bible. I looked up the word “holy” in a concordance (a book that lists all of the occurrences of a specific word in the Bible) and here is what I found.
“For I am the Lord your God. Consecrate yourselves therefore, and be holy, for I am holy. You shall not defile yourselves with any swarming thing that crawls on the ground. For I am the Lord who brought you up out of the land of Egypt to be your God. You shall therefore be holy, for I am holy.”
~Leviticus 11:44-45
“Speak to all the congregation of the people of Israel and say to them, You shall be holy, for I the Lord your God am holy.”
~Leviticus 19:2
“You shall be holy to me, for I the Lord am holy and have separated you from the peoples, that you should be mine.”
~Leviticus 20:26
“As obedient children, do not be conformed to the passions of your former ignorance, but as he who called you is holy, you also be holy in all your conduct, since it is written, 'You shall be holy, for I am holy.'”
~1 Peter 1:14-16
“Even as he chose us in him before the foundation of the world, that we should be holy and blameless before him.”
~Ephesians 1:4
The entire book of James deals with showing/proving our faith by our works.
As I was recently studying through the book of Ephesians, I found that is has quite a bit to say about holiness as well. Chapter 2 tells us that we are hopeless and helpless without Christ, but because of Christ, we can do good and be holy. Chapters 4 and 5 give many examples of what holy living looks like.
Do you see a pattern in these verses? The Israelites were given the law to show that they were different, that they belonged to God, that they had been set apart. These laws were intended to make them holy because GOD IS HOLY. I found the same things was commanded of Christians in the New Testament. Peter said, “As he who called you is holy, you also be holy in all your conduct.”
So, does it really matter how we live? Absolutely! It matters because God commands it. It matters because it is how we prove that we have faith. It matters because God is holy and we are made in His image, to reflect His holiness. Does that mean that God has always wanted us to be holy? Read Ephesians 2. Verse 10 say we are “created in Christ Jesus for good works.” God created man to do good works, to be holy. Chapter 1 verse 4 says God desired man to be holy and blameless. “before the foundation of the world.” It has always been His intention for man to live a holy life.
Once we have come to the conclusion that we should live holy lives, how do we do that? We plead with God to help us. We cannot do it by our own strength and power, but with God, nothing is impossible. If God wants you to do something, He will give you the strength to do it. You may have to ask for this strength daily, but God has promised to always be with us and He will give us that strength daily.