Pursuing holiness

In Chapter 7 of Joshua, an Israelite stole a sacred item. In response, God warns (Joshua 7:13, NLT),

You will never defeat your enemies until you remove these things from among you.

Centuries later, the author of Hebrews says (Hebrews 12:14, NLT),

Work at living a holy life, for those who are not holy will not see the Lord.

And, most famously (and dramatically), Jesus says (Mark 9:47, NLT),

If your eye causes you to sin, gouge it out.

All of these passages make the same point. That is, we must remove stumbling blocks to sin and strive for holiness. Why must we be holy? Why does God care how we behave? Well, we shouldn't need an answer; we should simply obey. But if we need an answer, God gives us an one, simply enough (Leviticus 20:26, ESV),

You shall be holy to me, for I the LORD am holy.

These passages should instill us with a sense of fear, but also with a sense of joy. After all, those who achieve this holiness will "see the Lord"!