Galatians 5:6 For in Christ Jesus neither circumcision nor uncircumcision has any value. The only thing that counts is faith expressing itself through love.
We like to keep up with other people by doing what they are doing, following fashions and allowing others to see something in us which is mainstream!
What Christ taught the disciples was that this all amounts to nothing; just like people wanted to become Jews and follow the Jewish ways, we like to follow on from other groups to make us look righteous in some way.
Christ looks at the heart and not the outward appearance, so nothing we do to show others our faith will amount to anything with Him; but doing some things can encourage others!