“I am the Lord your God; consecrate yourselves and be holy, because I am holy.” Lev 11:44.
God had a claim over the Israelites because He created them, chose them to be His, delivered them from slavery in Egypt and led them into the Promised land. Holiness is an attribute of God and Chambers Dictionary defines it as moral perfection, pure in heart. There is no standard of moral excellence that God has to adhere to since Holiness is an intrinsic attribute of His.
As humans, we lost the attribute of holiness from the fall. This pathetic situation brought about a disconnect between us and God. To change the situation, God commanded us to consecrate ourselves – set ourselves apart for Him only. We are then to make ourselves holy. What God was asking them to do was to observe some ceremonial laws as a sign of being set aside for the Lord. The outward observance of these laws did not do much to change their hearts. This same command is repeated in 1Peter 1:15 to the Church of Christ. The difference here is that we have been declared holy and righteous through the cleansing work of the blood of Jesus Christ. Because of this reality we strive hard to be ceremonially holy both externally and internally through confession and repentance.
We cannot earn holiness by what we do, but we strive to live holy lives through the Blood of Jesus because we are thankful for what God has already done. Do you desire and pursue holiness all the time?