Do not love the world nor the things in the world. If anyone loves the world, the love of the Father is not in him. (I John 2:15)
John is not saying that we should not love others, the Bible clearly tells us that we SHOULD love others (Matthew 19:19, 22:39; Mark 12:31, 33; Luke 10:27). He is saying that we should not be SO in love with the world that it comes between us and God. John is saying that we should not love the WAYS of the world or the world SYSTEM. We should not think as the world thinks. The world's priorities should not be our priorities.
John then specifies the things of the world that he is warning about:
16 For all that is in the world, the lust of the flesh and the lust of the eyes and the boastful pride of life, is not from the Father, but is from the world.
Lust is not merely a desire for something; it is the illicit desire for anything out of God's will for our life. It is wanting what God does not want us to want.
The 'lust of the flesh' is the powerful physical desires that can cloud our thinking at times if we don't keep them in check. The only sure way we have of conquering these lusts is through the power of the indwelling Holy Spirit. When we are controlled by God, we will be able to resist temptation (I Corinthians 10:13).
The 'lust of the eyes' consists of lusting after things in our mind. We see them with our eyes and, although we may never physically possess them, we mentally dwell on the possibility.
The 'pride of life' means attributing all the things we have, our success, our possessions, our health, etc., to our own abilities and power. It involves not thanking God for the things we have (Romans 1:21).
17 The world is passing away, and also its lusts; but the one who does the will of God lives forever.
Many people spend all their time and energy building chasing fame, success, wealth, and a host of other pursuits. All of these will either be lost or the person chasing them will die and leave it all behind. The bottom line is that all those things are temporary. The Bible says that it is wiser to invest in permanent things (Matthew 6:19-20).
A right relationship with God is forever.
Seeking to introduce people to Jesus Christ and to help them become "transformed by the renewing of their mind."