Several issues here given the Word of God.
1. There are many false or imposter Christians (Matthew 7:21-23). People who will be cast into hell despite being very active in their church by the sound of it. Now to be saved is still quite simple really once drawn by the Holy Spirit (Romans 10:9, Luke 11:13), but these simple acts are in fact quite difficult (Luke 13:23-25). It seems many hearts, even in the church, are far from God as it was in the days of ancient Israel (Isaiah 29:13, Matthew 15:8-9, Mark 7:6-8, Jeremiah 32:33).
2. There is a judgment of Believers based on our deeds in the flesh (2 Corinthians 5:10). These people may be saved but as through flames, which at the very least indicates pain at our folly (1 Corinthians 3:10-15).
3. There is a hierarchy in heaven (Matthew 11:11).
In addition, the knowledge of our Lord and Savior Jesus Christ (i.e. what is often called proper doctrine) is a virtue to pursue (2 Peter 1:5-9).