We are made up two personalities. There is the outward man–that is the person we can see with our outer eyes–while there is the inward man. The inward man cannot be seen with the naked eyes. Everyone, as long as they are not visually impaired, can see the outward man, but it is not the same for the man that is inward.
2 Corinthians 4:18 - While we look not at the things which are seen, but at the things which are not seen: for the things which are seen are temporal; but the things which are not seen are eternal.
The outward man can only live for a limited time. Whatever we can see and comprehend with our eyes doesn't have the tendency of existing forever. The same thing goes with our mortal bodies. On the other hand, spiritual things is meant to last forever. When we as humans die, our physical bodies dies off, but our inward man–which is our spirits–cannot die.
When dealing with God–being a spirit– we interact with Him as spirit to spirit. God doesn't look at the outward but looks inwardly. This is why the state of our spirits is very important. People who act all good but have a beastly nature inside of them deceives no other but themselves. God knows the true nature of every man. We should be good both on the outside and on the inside as well.
Other passages discussed in today's teaching are:
Jeremiah 6:16, 2 Corinthians 4:16, Matthew 7:15, 2 Peter 2:22, Romans 7:22, Genesis 1:26