Mark 7:14-16 (NKJV)
When He had called all the multitude to Himself, He said to them, "Hear Me, everyone, and understand: There is nothing that enters a man from outside which can defile him; but the things which come out of him, those are the things that defile a man. If anyone has ears to hear, let him hear!"
I heard my pastor say that if you want to see what a person is made of, just jostle them up and see what spills out. We put on our best faces for the world to see but so often it is all just a front. We think we might be doing something quite admirable but have we ever examined the true motivations that lie behind.
Jesus said "apart from me you can do nothing." If we desire please God, we need Jesus to do it through us. It is only by dying to sin and self and allowing Jesus to live in us that this is possible.
Jeremiah 17:9 (NKJV)
The heart is deceitful above all things, And desperately wicked; Who can know it?