God’s “Other Than-ness” (Holiness) Pt.1

1 Peter 1:14-16 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”. If holiness is “God’s all encompassing Attribute” what does it mean when God says I am Holy?