Many churches teach about Jesus Christ. The 10 Commandments, the birth of Jesus Christ, his mortal ministry, and his death on the cross at Calvary. They also teach about the Holy Bible as a complete book and prophets in the past tense.
They are teaching only half of the truth and declaring it complete. The problem is not what they are teaching, but how it is being taught. They are great subjects, but the Holy Bible is not the only piece of scripture that we have, nor are prophets only history. Jesus resurrected from the tomb after the cross, and lives today. Through his perfect example he did atone for our sins and allowed for us to be saved. There are modern day scriptures and prophets to help us to understand and know these things for ourselves.
By declaring half of the truth as complete allows pride to swell. This causes us to stop seeking more because we feel that we already have everything. In that lie to ourselves we loose valuable information including our knowledge for our reason to be here on this earth. More about the dangers of pride can also be found in “About The Pharisees“. More about modern day revelation can be found through The Church of Jesus Christ of Latter-day Saints.