“Do not be deceived, my beloved brethren”
Verse 16 is a transition between the preceding and the following verses, linking the ideas together. Those who blame God for their sin need to understand something about the nature of God.
Do not be deceived,
We get our English word “planet” from the Greek word for “deceived.” A planet wanders in the skies. Deception makes us wander from the truth.
James warns believers scattered in the Roman world against a particular misunderstanding about the nature of God (v.17-18). The most fundamental error we can make is misunderstanding the nature of God. If we attribute evil to the nature of God (v.13), we commit the most egregious error. God is the source of good (v.17), not sin.
my beloved brethren
James clearly loves those to whom he ministers. It is wonderful to be the object of love. It is one thing to be in the family of God; it is another to be loved as a member of the family of God.
“Therefore, my beloved and longed-for brethren, my joy and crown, so stand fast in the Lord, beloved” (Philippians 4:1).
The doctrine of God is the foundational doctrine of Christianity.
If we go astray on the doctrine of the nature of God, we will wander into error. People can deceive us about the nature of Christianity. We will move into all kinds of irregularities doctrinally.