Question: "How should a Christian view materialism?"
Answer: Materialism is defined as "the preoccupation with material things rather than intellectual or spiritual things." If a Christian is preoccupied with material things, it is definitely wrong. That is not to say we cannot have material things, but the obsession with acquiring and caring for "stuff" is a dangerous thing for the Christian, for two reasons.
First, any preoccupation, obsession, or immoderate fascination with anything other than God is sinful and is displeasing to God. We are to "love the Lord, your God, with all your heart, and with all your soul, and with all your might" (Deuteronomy 6:5), which is, according to Jesus, the first and greatest commandment (Matthew 22:37-38). Therefore, God is the only thing we can (and should) occupy ourselves with habitually. He alone is worthy of our complete attention, love, and service. To offer these things to anything or anyone else is idolatry.
Second, when we concern ourselves with the material world, we are easily drawn in by the "deceitfulness of wealth" (Mark 4:19), thinking that we will be happy or fulfilled or content if only we had more of whatever it is we are chasing. This is a lie from the father of lies, Satan. He wants us to be chasing after something he knows will never satisfy us so we will be kept from pursuing that which is the only thing that can satisfy—God Himself. Luke 16:13 tells us we "cannot serve both God and money." We must seek to be content with what we have, and materialism is the exact opposite of that contentment. It causes us to strive for more and more and more, all the while telling us that this will be the answer to all our needs and dreams. The Bible tells us that a person's "life is not in the abundance of the things which he possesses" (Luke 12:15) and that we are to "seek first the kingdom of God and His righteousness" (Matthew 6:33).
If materialism were ever to satisfy anyone, it would have been Solomon, the richest king the world has ever known. He had absolutely everything and had more of it than anyone, and yet he found it was all worthless and futile. It did not produce happiness or the satisfaction our souls long for. He declared, "Whoever loves money never has money enough; whoever loves wealth is never satisfied with his income" (Ecclesiastes 5:10). In the end, Solomon came to the conclusion that we are to "fear God, and keep His commandments. For this is the whole duty of man" (Ecclesiastes 12:13).