"Do not let your heart envy sinners, but be zealous for the fear of the Lord all the day; for surely there is a hereafter, and your hope will not be cut off" (Prov. 23:17-18).
Solomon warned that we are not to envy sinners. There is a temptation to envy those who appear to have it easier or better than us. Sinners have this appearance because they are not walking in the fear of the Lord. That is, they have dismissed the idea that they are accountable to God and thus live without any moral restraints. They appear to have fun in this life while we do our best to deny ourselves and abstain from sin.
However, the Bible warns us not to envy such people. Their apparent enjoyment of life is only a temporary condition. Sinners appear to enjoy life in the here and now, but the "here and now" is all they will have. As one has said, "If someone dies and goes to Hell, this life will be all the Heaven they will know." What a sad thought. The sinner is someone who has lost sight of the fact that there is a hereafter. They have traded their eternal soul for a few years of happiness. Such a person is to be pitied, not envied.
If we envy sinners we will likewise lose sight of eternity. The wise Christian understands he is in a marathon - not a forty yard dash. The wise Christian understands he is a stranger and pilgrim here in this life - not a resident. A wise Christian will not trade his eternal birthright for a bowl of the world's best porridge to satisfy a temporal and immediate appetite (Heb. 12:16). A wise Christian understands the weight of eternity, and is zealous for the fear of the Lord all the day.