Make every effort to live in peace with everyone and to be holy; without holiness, no one will see the Lord. (Hebrews 12:14 NIV)
God has called us to live a holy life. God would not have commanded this if it was impossible to live a holy life.
We are not made holy by doing good things. We are made holy by faith in Christ, just as our faith in Christ saves us. Little by little, as we grow and live with the Lord, we become more like Him. We become like Him because we are set apart with Him. This is true holiness.
“God's will is that we would be righteous in our living. God is holy, and the whole scheme of redemption has holiness for its goal.” - Billy Graham