The Lord Jesus Christ proclaimed that he is the Truth. The opposite of Christ is antichrist; the opposite of the Lord Jesus Christ is the devil himself. “When he lies he speaks his native language, for he is a liar and the father of lies” (John 8:44).
The believer in Christ is able to discern by the power of the Holy Spirit what is of God and what isn’t. “We have the mind of Christ” (1 Corinthians 2:16). The problem is that most Christians do not know this is true, or do not believe it to be true. But God has renewed our minds (Romans 12:2). It is true.
Unfortunately, the believer is not untouchable by the devil’s lies. Satan is still the tempter and deceiver, even to those set free by Christ. He tempted Adam and Eve in the garden before they had ever sinned. He tempted Jesus Christ in the desert, and he did not sin. The Christian is not untouched by the devil’s attacks, to the lies that the forbidden fruit is really sweet and God didn’t really mean what he said.
However, the Christian has been set free and has been given the power over the devil and his schemes. Our position in Christ Jesus is a position of victory, Satan being crushed under the feet of our glorious Lord (Ephesians 2:6). Because of who we are in Christ, we already have victory. We just need to walk in it.
We talk a lot about truth here, about the existence of absolute truth and what that truth is exactly. Christians do not deny these things. However, sometimes the Christian may be tricked into believing lies of other sorts, usually pertaining to sin. Do not be deceived. If you believe in the truth of the gospel, always, always measure up your thoughts and your very life to that measure. Pray without ceasing. Be in tune with the Holy Spirit. Seek God’s face at all times. If you do these things you will not be led astray. You will know the lie when it shows itself. And you will overcome.