What the Bible says about Shifting Foundation
(From Forerunner Commentary)
Christ knew that some coming to build would be attracted to a ready-prepared level surface of sand rather than to sites that must be excavated to reach the hard and rugged rock. Human nature often chooses what looks easy on the surface. But after the seasonal floods, representing trials and tests, such a builder would have nothing left but a heap of ruins. A sandy foundation represents empty preference and mere external religion based on false knowledge. The sand reflects the shifting, uncertain feelings some foolish people possess, the only ground upon which they act. The second house, even though most impressive, stands on a shifting foundation, and is therefore doomed to destruction. People whose resolves do not rest on God's help sought in prayer—people who have virtues without root—live in a dangerous position (II Samuel 22:4-5). The Pharisees built their hopes on external blessings and privileges, which alienated their minds from the Rock of their salvation. Christ had to tell them that Satan, not Abraham, was their father.
Martin G. Collins
Parable of the Two Builders