Philippians 2:14-17, “Do all things without murmurings and disputings: That ye may be blameless and harmless, the sons of God, without rebuke, in the midst of a crooked and perverse nation, among whom ye shine as lights in the world; Holding forth the word of life; that I may rejoice in the day of Christ, that I have not run in vain, neither laboured in vain. Yea, and if I be offered upon the sacrifice and service of your faith, I joy, and rejoice with you all.

1. Light shines unless it is hindered.

Matthew 5:14-16 Ye are the light of the world. A city that is set on an hill cannot be hid. Neither do men light a candle, and put it under a bushel, but on a candlestick; and it giveth light unto all that are in the house. Let your light so shine before men, that they may see your good works, and glorify your Father which is in heaven.

v. 14 shows us that murmurings and disputing are hinderances to our light.

v. 15 shows us 3 things that will help our light shine more brightly: That ye may be blameless and harmless, the sons of God, without rebuke, in the midst of a crooked and perverse nation, among whom ye shine as lights in the world;

'Blameless' doesn't mean you don't do wrong, but that when you do, you make it right. 'Harmless' is different than blameless. Blameless is in the eyes of others. Harmless is in your own eyes. It is knowing in your heart that you are sincere and that your motives are pure. ‘Without rebuke' pertains to the eyes of God. It means you don't give God reason to correct you. It doesn't mean sinless, but rather that your sins are confessed and you are attempting to forsake them.

2. Light shares.

v. 15b Light is intended to shine in the darkness of the world.

2 Peter 1:19, “We have also a more sure word of prophecy; whereunto ye do well that ye take heed, as unto a light that shineth in a dark place, until the day dawn, and the day star arise in your hearts:”

3. Light sacrifices. v. 17, “Yea, and if I be offered upon the sacrifice and service of your faith, I joy, and rejoice with you all.”

As a candle burns, the wax is spent. 
As flashlights shine, they consume batteries 
As oil lamps shine, they consume oil and a wick. Are you consumed with a cause? Is your light shining or is it hindered?