A.B. Simpson emphasizes the importance of holding onto foundational truths while being open to new revelations from God. He warns against the danger of constantly abandoning established beliefs for fleeting new ideas, which can lead to spiritual instability. Simpson encourages believers to build upon the truths they have already learned, ensuring that their faith is rooted and grounded. He reminds us that God desires to expand our understanding without compromising the core principles of our faith. Ultimately, we are called to prove all things but to hold fast to what is good and true.

It is good to be able to receive new truth and blessing without sacrificing the truths already proved or abandoning foundations already laid. Some persons are always laying the foundations, until, finally, they appear like a number of abandoned sites and half-constructed buildings. Nothing is ever brought to completion. If today you are abandoning for some new truth the things that a year ago you counted most precious and believed to be divinely true, this should be sufficient evidence that a year from now you will probably abandon your present convictions for the next new light that comes to you. God wants to continually add to us, to develop us, to enlarge us, to teach us more and more but always building on what He has already taught us and what He has established in our lives. While we are to prove all things, let us hold fast that which is good, and whereto we have already attained, let us walk by the same rule, let us mind the same thing (Philippians 3:16).