Paul told the saints at Thessalonica to "test everything that is said" and "hold on to what is good." (I Thessalonians 5:21) He told Timothy to "hold on to the pattern of wholesome teaching you learned from me" (II Timothy 1:13) and "carefully guard the precious truth that has been entrusted to you." (verse 14) The author of the Epistle to the Hebrews wrote "Let us hold tightly without wavering to the hope we affirm." (Hebrews 10:23) In his messages to the churches of Thyatira and Sardis, Christ instructed them to keep a firm grip on the truths which they had previously received (Revelation 2:25 and 3:3).
Unfortunately, many Christians have interpreted these scriptures to mean that they should automatically reject anything that doesn't conform to what they already know. When faced with something new or unfamiliar, it's almost as if these folks completely shut down. They turn into the kid who closes his eyes as tightly as he can and uses his index fingers to plug his ears. For many people, this is what it means to protect the truth which God has revealed to them; but is this what God intended?
For these folks, God's truth is a very fragile thing that can easily be lost. They live in fear of sliding back into that state of deception from which God's calling has delivered them. They are always one step or stumble away from perdition! If they do slip, many of them are convinced that they will never find their way back (Luke 9:62, Romans 1:21 and Hebrews 10:26). But wait, didn't John say that "perfect love expels all fear." (I John 4:18) Can anything good originate in fear? Can the fear of damnation keep someone from falling into error?
In the book of Acts, we are told that the Bereans were "more open-minded than those in Thessalonica, and they listened eagerly to Paul's message." (Acts 17:11) Continuing, we read: "They searched the Scriptures day after day to see if Paul and Silas were teaching the truth." (same verse) Remember, Paul said to "test" what is said (see above). Likewise, John instructed his readers to "test" spirits to make sure that they were from God (I John 4:1). In other words, if something that you believe is TRUE, you shouldn't have anything to fear from further study and examination! Indeed, further exploration should arrive at the same conclusion if it's really TRUE. And, if you don't arrive at the same conclusion, then your original understanding must have been faulty!
Peter's statement that we "must grow in the grace and knowledge of our Lord and Savior Jesus Christ" (II Peter 3:18) implies a lifelong process. For many Christians, spiritual understanding is a static thing. They think: "If I have THE TRUTH, then I don't need to hear anything else!" Their belief system becomes a closed and self-reinforcing process that is impervious to new truth or information. This isn't called growth - it's called stagnation. Such an understanding isn't founded upon a rock - it's built on sand.
What about you? Are you still growing in grace and knowledge or have you already absorbed all of the available truth? Have you attained a level of Spiritual understanding that doesn't require any further input from your brothers and sisters in Christ?