When the Lord asked Abraham as to why Sarah laughed, when she heard of the promise of a child that she would bear, the Bible records that out of fear, she lied to the Lord saying that she did not (Genesis 18:15). To this the Lord does not react angrily but reaffirms that even the hidden laughter of Sarah was not hidden from the Lord. In fact, by denying what the Lord was stating was making God a liar, which Apostle John reaffirmed in 1 John 1:10 which reads “If we say that we have not sinned, we make him a liar, and his word is not in us.”

From this account we can learn a few things
1. Fear causes us to lie, but since those who live according to God’s spirit have no condemnation in Christ, there is no need to fear, which means that there is no need to lie (to God).
2. One cannot lie to God and get away with it, because he is omniscient.
3. Lying to God and denying that we have not sinned, when we have, makes God a liar (1 John 1:10) and God is not a man that he should lie (Numbers 23:19).

Lying to God is no laughing matter.

Points to ponder:
The Bible states that the father of lies from the very beginning is the devil (John 8:44). Jesus said that he and the Father are One and that he is The Truth (John 14:6). In him, there is no condemnation (Romans 8:1) i.e., no need to fear.
Are you living in fear or with a sound mind without timidity? (2 Timothy 1:7)
We may be able to lie to man and get away with it, but we cannot lie to God and get away with it?
Lying to God makes God a liar and since he is God, the personification of Truth itself, he cannot lie and this is no laughing matter.

Genesis 18:15 (KJV)
15 Then Sarah denied, saying, I laughed not; for she was afraid. And he said, Nay; but thou didst laugh.

John 14:6 (KJV)
6 Jesus saith unto him, I am the way, the truth, and the life: no man cometh unto the Father, but by me.

2 Timothy 1:7-10 (KJV)
7 For God hath not given us the spirit of fear; but of power, and of love, and of a sound mind.
8 Be not thou therefore ashamed of the testimony of our Lord, nor of me his prisoner: but be thou partaker of the afflictions of the gospel according to the power of God;
9 Who hath saved us, and called us with an holy calling, not according to our works, but according to his own purpose and grace, which was given us in Christ Jesus before the world began,
10 But is now made manifest by the appearing of our Saviour Jesus Christ, who hath abolished death, and hath brought life and immortality to light through the gospel: