Romans 10:17, So, faith comes from hearing, and hearing through the Word of Christ.
There are many reasons why all Christians ought to attend church, but the sole reason is this: that faith be received. This is why there is preaching, that people might hear the Word of Christ and thus receive faith as the Spirit wills (Romans 10:14-15). “But I already have faith,” some might say. That is a lazy excuse, for faith always needs sustaining, and it is the Word of Christ that sustains it, and the Word of Christ is preached nowhere but in the Church.
Again, someone might interject, “But I can read the Word at home.” Yes, you can, but you are part of the body of Christ, which is full of many members (1 Corinthians 12), and no member is meant to be left alone. Yes, you can read the Word in the privacy of your home, but faith also needs the instruction of your shepherd, for one’s private interpretation can lead one astray.
Contrary to popular belief, faith is not a private practice; that is an American notion. Faith is first and foremost a communal effort. God’s faithful children gather together to hear the Word of His Son, we gather before the Lord’s Table together to partake of Jesus’ body and blood for the forgiveness of all our sins, we live life throughout each week with one another (for worship does not pertain merely to one hour on Sunday), and we live out our faith by loving our neighbour throughout the week.
If you wish to have a private faith, you cannot call yourself a Christian, for Christians, as God’s children, are brought into a family who hear the Word together, eat together, and live life with one another. We also aim to bring others into God’s family, which cannot be done in isolation.
The Lutheran Column 