How do we know what is true?

The Certainty of the Bible
Matthew 1-5
“For truly I say to you, until heaven and earth pass away, not the smallest leter or stroke shall pass from the Law until all is accomplished.” (5:18).
Where do we discover truth? Where do we find it, and to whom do we turn to discover what is morally right? This is the most fundamental question about life we can ask. Everyone will answer this question in their quest to determine how to live. Some turn inward and trust their own wisdom and understanding. They follow the adage, “Let your conscience be your guide.” To determine what is true, they look inward to their own reasoning. People thus say, “Be true to yourself.” However, we can easily be self-deceptive. Jeremiah warns us, “The heart is more deceitful than all else and is desperately sick; Who can understand it” (Jer. 17:9). So also Proverbs warns us, “There is a way which seems right to a man, but its end is the way of death” (14:12). To trust in oneself is to be self-deceived, for we fail to recognize the power of sin’s grip upon our life.
Others turn to society and the popular opinion of people. Morality and truth are determined by popular vote. What the majority believes determines what is true. Thus, morality is always shifting according to the popular opinion of people. What was viewed as wrong in previous generations is now considered right, for morality is shifting as the opinions and views of people change. But here again we find a fatal flaw: just as sin corrupts the individual’s moral compass, it also corrupts society's moral compass. Paul warns against the popular opinion of our culture when he writes, “Do not be conformed to this world” (Romans 12:2). So also John warns us that if we pursue the morality of the world and its values, then the love of the Father is not in us” (1 John 2:15).
So where do we turn to discover what is true? Christ provides us with the answer in Matthew 5:18-19. Some say the Old Testament law is invalid, written by men expressing their views. Therefore, the only standard of truth is the words of Christ, and the rest of the Bible is merely the opinions of unenlightened men. However, Christ does not give us this option. In his Sermon on the Mount, Christ makes it clear that the writings of the Old Testament law did not originate with man but came from God, and thus they are 100 percent true and accurate. We cannot reject them as outdated, for they originate from God, and those who reject the teaching of the law are not only false teachers but will face the certainty of God’s judgment.
This confronts us with the question: Do we trust in God’s word, revealed to us and recorded by the writers of the Bible, who wrote by the direct inspiration of God? Do we turn to the words Christ affirmed to be true or to the opinions of people? How we answer this question will determine our eternal destiny. Psalm 1 states, “How blessed is the man who does not walk in the counsel of the wicked, nor stand in the path of sinners, but sin in the seat of scoffers! But his delight is in the law of the lord, and in His law he meditates day and night.”