Our skin is soft, like tightly woven fabric. It appears porous from the outside—with millions of tiny openings that ooze sweat. But you might be surprised to learn how effective a barrier our skin can be.

For decades medicine makers have tried to develop drugs that can be administered through the skin. Doctors call them "transdermal" drugs—like some pain-relieving sprays and nicotine and hormone patches. Pharmaceutical companies are racing to perfect a way to make drugs that can be accepted this way—and painlessly.

But for all the work, they have only been able to find a handful of compounds that go through our skin. However, if our skin is prepared—temporarily altered—medicines can permeate it. Scientists have developed ointments that make the skin able to transmit drugs. They've used very low electrical currents to propel drugs through the skin. They've even invented little patches about the size of a band-aid with tiny microneedles that pierce the top layers of the skin enough to get drugs in but not deep enough to be felt by our nerves.

All of this to try to overcome the barrier of our skin.

Spiritually we're the same. Our hearts have barriers. We can be immersed in God's grace, but at times none of it permeates into our hearts. Judas spent over three years up-close with Jesus himself, but in the end He handed Jesus over to be murdered for 30 pieces of silver. A child can be raised by godly parents, hearing Bible stories and earnest prayers at home, faithfully attending church every Sunday, but then grow up to be a prodigal who never returns.

Sometimes the problem isn't the environment. Sometimes the problem is that we are impenetrable to the gospel. Just as the skin must be treated to transmit medication to the body, so our souls require the special work of God's grace before we can receive the life and healing that he wants to bring.