Yes. God did know, and He trusted this family to keep their convictions. Because He knew they'd stay true to their values, He chose to use them as an illustration to the entire nation of Judah. The message to Judah: "This family can honor an ancestor's request, but you won't listen to Me, even though I'm God."
Once the proclamation was made, God honored the Rechabite's devotion. "And Jeremiah said unto the house of the Rechabites, Thus saith the Lord of hosts, the God of Israel; Because ye have obeyed the commandment of Jonadab your father, and kept all his precepts, and done according unto all that he hath commanded you: Therefore thus saith the Lord of hosts, the God of Israel; Jonadab the son of Rechab shall not want a man to stand before me for ever" (Jeremiah 35: 18-19).
Notice what distinguishes this behavior as one of honor rather than one of rebellion.
1. It went above and beyond the call of duty. The things that set this family apart did not bring a reproach to anyone else who would have been a God follower.
2. The purpose of the rule was to honor God and humble the flesh. The forefather who had issued the command was establishing memorials of remembrance for what God had done and praising Him for His mighty acts. He was also giving a physical reminder to his family to place little value in comforts, to live a simple lifestyle, which, by default protected their health and well-being.
3.The motive for continuing the lifestyle was pure, not obligatory. The family had chosen to follow these commands for the purpose of unity and honor, not to disparage anyone else.
Our convictions are much the same. They vary among individuals because they are personal ways of stating, "As for me and my house, we will serve the Lord." They establish parameters that define us, that help us remember what God has done, and that bring honor to Him. As a result, they become a wall of defense around us, keeping out many things that could cause harm.
Just like the Rechabites, we, too, may experience a time of testing when it looks like God is challenging our sacrifices. Do we really believe what we say we believe? Will we hold fast to the best when the good is offered? Will we do more than what is required or expected? If we have settled the issues in our hearts, then we will answer these questions with assurance, knowing that God supports our above-and-beyond attitude, and the response will be the smile of God. He will honor our honor with blessing that far supersedes our sacrifice.
Tip/Tidbit: Write your personal convictions. Draw a circle around them. Are these consecrations settled in your heart, or could circumstances change your adherence them?