Proverbs 3:5
Trust in the Lord (YHWH} with all your heart, and do not lean on your own understanding.
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Probably one of the very best reasons not to lean on our own understanding is revealed through the prophet Isaiah when God spoke and said: “For My thoughts are not your thoughts, neither are your ways My ways, declares the Lord. For as the heavens are higher than the earth, so are My ways higher than your ways and My thoughts than your thoughts.” (Isaiah 55:8-9)

We need to, and are told to, do everything according to the Word of God which is the source of our faith {Rom.10:17} otherwise we will be doing what we do in 'lower ways' with 'lower thoughts', or to put it more simply, the world's ways. We know that without that faith it is impossible for us to please God {Heb.12:2} so whatever we do according to our own understanding will be most likely displeasing to God.

Doing everything by faith is more than just achievable, it should be the norm for all true Christians because the Lord has given us everything pertaining to life and godliness. {2Pt.1:3} Even Jesus Himself did not do all the things that He did on His own. As He said, “I can do nothing on my own. As I hear, I judge, and my judgment is just, because I seek not my own will but the will of Him who sent me.” {Jn.5:30} And, “For I have not spoken on my own authority, but the Father who sent me has Himself given me a commandment—what to say and what to speak.” {Jn.12:49}

Jesus had said that He would build His church {Mat.16:18}, a people, not a building, but it seems evident that it was not long before so many of those people said, at least in practice, 'Don't worry, we will take care of that!' and have built institutions based on their own understanding. So called churches that do not look like or act like the Word of God instructs us to be! The very last book of the bible, Revelation, looks at the seven churches of Asia Minor that basically represented the entire church of the time, as well as the entire church of our day. They were messages from the Lord to teach, reprove, correct and train in righteousness. {2Tim.3:16}

And so we have been warned:

“Let no one defraud you, insisting on self-abasement and worship of angels, going on in detail about visions, puffed up without reason by his sensuous mind, and not holding fast to the Head, from whom the whole body, nourished and knit together through its joints and ligaments, grows with a growth that is from God.
    If with Christ you died to the elemental spirits of the world, why, as if you were still alive in the world, do you submit to regulations— "Do not handle, Do not taste, Do not touch" (referring to things that all perish as they are used)—according to human precepts and teachings?
    These have indeed an appearance of wisdom in promoting self-made religion and asceticism and severity to the body, but they are of no value in stopping the indulgence of the flesh.”
(Colossians 2:18-23)

BE LED BY THE SPIRIT OF GOD—HIS WAYS ARE HIGHER