Answering the Question
Several posters have said Paul wrote Hebrews 3:12 Questionable at best, misinformation at worst.
Anyway, what was the idea? How can we see to it that none of us (professing believers) has a sinful unbelieving heart? The church has wheat and tares, folks who have been born anew, and folks whose faith God has yet to accept. What are we supposed to do help those we fellowship with? We are to set an example of integrity and candor, eschewing deceitfulness, such that we continue to grow and those we influence will continue to be cultivated such that their faith grows in their heart as opposed to lip service profession.
Bottom line, the lost which includes professing tares, can continue in the deceitfulness of sin and harden their hearts, or we can provide witness that we are "all in" for Christ and help them grow in heart-felt faith.
According to the false doctrine of Total Spiritual Inability, all the lost have no receptivity in the heart to harden, it is already hardened from conception. So right off we know the Calvinists will say Paul did not really mean what he said.
But if you study the verses that address loss of ability, and there are lots of them, you see that the lost have limited spiritual ability and can lose it, which yet again demonstrates the T of the TULIP is false doctrine.
Several posters have said Paul wrote Hebrews 3:12 Questionable at best, misinformation at worst.
Anyway, what was the idea? How can we see to it that none of us (professing believers) has a sinful unbelieving heart? The church has wheat and tares, folks who have been born anew, and folks whose faith God has yet to accept. What are we supposed to do help those we fellowship with? We are to set an example of integrity and candor, eschewing deceitfulness, such that we continue to grow and those we influence will continue to be cultivated such that their faith grows in their heart as opposed to lip service profession.
Bottom line, the lost which includes professing tares, can continue in the deceitfulness of sin and harden their hearts, or we can provide witness that we are "all in" for Christ and help them grow in heart-felt faith.