Squirrels run through trees and eat nuts.  Eagles soar in the sky and hunt squirrels.  Otters play in rivers, and lions lie in grasslands.  Bats sleep during the day and fly at night, while spiders build webs and wait. 

Squirrels do not act like eagles, and bats do not act like spiders.  Creatures behave in accord with what they are.  Their DNA affects how they live. 

The spiritual world is the same way.  Who you are determines how you live.  John wrote that those who abide in Christ do not continue in sin because God’s seed is in them. (I Jn 3).  Yet this same John also said that if we say we have no sin we deceive ourselves and the truth is not in us (I Jn 1:8). 

The Christian is, thus, someone who still sins but who does not continue in sin.  Sin is not our home.  It is not our habit.  It is not our lifestyle.  Even if we may fall into it and be impure as a result. 

The Christian needs forgiveness because he still sins, but the Christian has a new DNA from above and has changed.

This is why Scripture will say that Christians are righteous and then say that they need to confess their sins.  We are new creatures who still live in our fallen bodies and within this fallen world.  We are salmon swimming upstream against this world, but sometimes the current catches us and we fall back into the ways of the world.

The way to tell the difference between a genuine Christian and a false one is by looking at the overall direction – the pattern – of his life and not with a single incident.  Even in looking at the pattern we can be mistaken, for we can mistake reality, and a Christian is more than behavior.  But you will tend to be more accurate if you look holistically at a person and not just at the particular sin or act that irritates you. 

Christians are new but not perfect.  We err when we neglect either of those truths.  Some people expect perfection and, consequently, show no grace to their brothers and sisters.  Other people excuse sinful lifestyles under the guise that Christians are not perfect and, in doing so, compromise the Christian witness to the world. 

When God makes Christians new, He does so from the inside out.  He changes who you are.  It’s like going from a squirrel to an eagle.  The behavior will follow.  It may not follow immediately or perfectly, but it will come.  A new heart that never results in a new life is not a new heart.  Continued sin is evidence of an old heart.  A changed life is evidence of a new heart.  But if, in your changed life, you find that you still sin, do this:  repent, seek forgiveness, be cleansed, and move on.