Therefore, prepare your minds for action; be self-controlled; set your hope fully on the grace to be given you when Jesus Christ is revealed. As obedient children, do not conform to the evil desires you had when you lived in ignorance. But just as he who called you is holy, so be holy in all you do; for it is written: "Be holy, because I am holy.
| 1 Peter 1:13-16 |

Verse 13 & 14 says asks us to be different. As Christians, God expects a different way of life. Different from what we used to be like. Whats the use of calling ourselves Christian if we think, speak & act like the world? He has called us to be set apart for Him.
Verses 15 & 16 says we are to be Holy because He is Holy. Because thats the only way we'll be able to relate to Him. The verse quotes a phrase quite commonly used in Leviticus in the old testament. Be Holy for I am Holy. This was God's command to Israel. A nation that God had chosen and set apart from the rest of the world. He had big plans for it and they required higher expectations.

When someone has high expectations of you, in a way it means that that person believes that you have the ability or the potential to reach those expectations. But God is the one who provides the means for us to reach those expectations. Such that we need not be overwhelmed.

Sidenote:Its interesting to read that in Leviticus 19:28, it speaks against having tattoos or cuttings (piercings) of any kind. But in the verse before that, it also speaks against having your hair cut or your beard trimmed.