Wash you, make you clean; put away the evil of your doings from before my eyes; cease to do evil (Is 1:16)
Of all the commentaries I've read on this particular verse, Gill's Exposition seems to hit the nail on the head: "Cease to do evil; either from ceremonial works done with a wicked mind, or from outward immoralities".
We can pray on our knees and praise God until the cows come home, but if we are living in sin, refusing to bend towards what is commanded of us, we are not living in his will. You can't say you are faithful to God if you are living a life that contradicts what he asks of you! We will never lead an entirely sinless life, but we are commanded to ~ that means we have to try. It means to abstain from what is "evil" or has the appearance of "evil" -- what is wrong, what is immoral and what is not "holy". And how much more vulgar is it to actually go through the motions and present yourself to be something that you are not? There is a "human" law against impersonating someone in power; how much more dangerous it must be to impersonate a Christian! I don't think I want to be judged in THAT court!
There are some things that just cannot be reckoned with either in our minds or in the reality that is given to us in God's word of truth. When a child first picks up a crayon and begins to color, the scribbling is always outside the lines. As he becomes more proficient with the crayon, the artwork begins to fill the object with more color inside and less outside. Once he has mastered the skill - very rarely does the crayon stray from within the boundaries laid before him - however, it does occasionally cross the line, but not nearly as often as it did when he first began to color. The same is true for our Christian lives! When we first begin our walk with God, at the first acceptance of Jesus as our Savior, we begin to learn what it is that is expected of us. With prayer and strength from the Holy Spirit, we change. Our focus becomes that of "Godly" things - we learn to stay within the boundaries of his Word. Even "seasoned" Christians sin! God knows this, he understands this.
We need to come to a point where everything we do is within the command of our heavenly Father, not the church we attend or the people we surround ourselves with. We won't always get it right, but we need to strive for it just the same. We can't change what God's word means or interpret it to fit the decisions we make. Our choices need to reflect the Word! Remember, one day you will stand before him and he will judge your actions (or inactions). Call upon the Holy Spirit to give you the strength to do what is right, not what is easy! Coloring outside the lines may get you noticed, but it won't get you anything of value! Focus on coloring within the lines and with his mercy and grace, you will see a beautiful picture of love - God's love!