"Then, when desire has conceived, it gives birth to sin; and sin, when it is full-grown, brings forth death" (James 1:15). Simply because a person is tempted doesn't mean that they've sinned; it's only when that desire conceives that sin is committed. When a person gives in to temptation, then their desire has conceived and sin is the result.
It takes two people to conceive a baby, and it takes two elements to conceive sin: (1) our desire and (2) Satan's enticement. And, just as babies grow up and mature into adults, sin grows up and ultimately leads to spiritual death; that is, eternal separation from God! Romans 6:23 teaches - "For the wages of sin is death..." The only time in which sin doesn't lead to spiritual death is when one comes to the Lord on His terms (which includes repentance; Luke 13:3).
James 1:16 reads - "Do not be deceived, my beloved brethren." James issued a warning here because of his love; he doesn't want Christians to give birth to sin. We need to beware because it is so easy to be deceived.
The little fish that has been told by its mother not to leave the group sees the worm dancing about and thinks: Why shouldn't I dart over there and gobble up that worm and then get back in place? Will anyone ever know? That is how little fish get drawn off course and deceived. Humans deceive themselves in the same way. We think that no one will ever know if we do a particular thing and then quickly slip back into place. How many think each day: What harm would it cause for me to gamble? Or lie? Or cheat on my spouse? Or drink alcohol? Friends, don't be deceived! Our "evil desires" draw us into sin and then sin enslaves us (cf. Rom. 6:16-18)! No alcoholic ever wanted to be addicted; no drug addict ever wanted to be hooked. But, the fact is that they gave in to their temptations originally because they wanted to. When we sin, we can't blame anyone but ourselves! Therefore, don't be deceived by sin and don't fool yourself into thinking that God is at fault!
"Every good gift and every perfect gift is from above, and comes down from the Father of lights, with whom there is no variation or shadow of turning" (James 1:17). James has already told us that evil is not from God; God doesn't tempt us. In fact, it is just the opposite. God is the source of all good; the gifts He bestows are pure, righteous, and complete. All that is good ultimately derives from God! And, just as the blessings come down, our gratitude should go up.
God is the Father of lights; that is, He is the originator or creator of all light--the sun, moon, stars, etc. "God is light and in Him is no darkness at all" (I John 1:5). There is no variation or shadow of turning with God which simply means that His nature doesn't change! The sun changes and the shadows change, but God doesn't! He is constant in His goodness! He is not the father of temptation because temptation is not a good gift! Thus, it could not come from God! He only gives good gifts! And, what better gift could He give than the gift of eternal life through His Son (John 3:16)?
The section closes with James 1:18 - "Of His own will He brought us forth by the word of truth, that we might be a kind of firstfruits of His creatures." James has already said that if we submit to our unlawful desires then sin will be born as a result. But, it is also true that if we submit to God, then we will be spiritually reborn as His children! God brings us forth by His word (cf. I Pet. 1:22,23)! God desires that we be saved. It is His will that we obey the gospel and have our sins forgiven.
The Christians in the first-century were God's firstfruits in the sense that they were the first Christians of a great harvest to follow. We are a part of that harvest today if we live as faithful slaves to the Most High God.
Let us summarize these powerful verses before we close. Evil may not be blamed on God because it is the result of man's improper desires. Eventually, giving in to improper desires leads to spiritual death. Christians need to remember that God is the source of all good, and it is through the power of His word that we become His children.