Ephesians 5:1-2
This passage opens by declaring the essence of the Christian life.  The mark of a true child of God is that they are a follower of God.  Jesus made a similar statement in John 15:14 when He says we are His friends if "we do whatsoever I command you."  This obedience is marked by love.
That love is shown in two ways.  First, to our fellow man by having a humble and sacrificial spirit.  This spirit was exemplified by Christ in His incarnation.  Philippians 2:5-8 tells us the same message.  Jesus Christ gave up Heaven, made Himself of no reputation, became a servant, and obeyed even unto death.  That is our example!
Second, our love is shown to God through obedience to His statutes.  There is a movement in churches today that rejects setting limits on people's lifestyles and calls that being judgmental and unloving.  However, as we look in this passage, we see that nothing could be farther from the truth.
The next 48 verses (Eph. 5:3-6:18) set down a long list of rules, regulations, and guidelines for how to "walk in love."  In fact, Ephesians 5:11 admonishes us to reprove the works of evil.  It is part of our duty to show those who choose the paths of evil the error of their ways and correct them.  I liken this duty to that of a parent.  If a parent sees a child doing something that will harm the, which response shows more love?
    a.  I don't want to be judgmental.  I might "turn them off" if I stop them.  Who am I to decide what's right for someone else?

    b.  I must warn them of the danger immediately before it's too late.

We would all agree on option "b".  And that is how we show Godly love to others.  By lovingly showing them the depth of their sin and pointing them to the Saviour.