Be not carried about with divers and strange doctrines. For it is a good thing that the heart be established with grace; not with meats, which have not profited them that have been occupied therein.
Hebrews 13:9 KJV
The word ‘strange’ in Scripture is use for anything that is not specifically commanded by God. The Israelites were to marry other Israelites but the men marry stange wives. Some men decided they could be priests and offered offered incense not in accordance with the Lord instructions.
Ezra 10:10 KJV And Ezra the priest stood up, and said unto them, Ye have transgressed, and have taken strange wives, to increase the trespass of Israel.
Leviticus 10:1 KJV And Nadab and Abihu, the sons of Aaron, took either of them his censer, and put fire therein, and put incense thereon, and offered strange fire before the LORD, which he commanded them not.
Hence, strange doctrines would be false teachings.
Hebrews 13:9 KJV Be not carried about with divers and strange doctrines. For it is a good thing that the heart be established with grace; not with meats, which have not profited them that have been occupied therein.
2 Timothy 4:3-4 KJV For the time will come when they will not endure sound doctrine; but after their own lusts shall they heap to themselves teachers, having itching ears; 4 And they shall turn away their ears from the truth, and shall be turned unto fables.