Micah 6:8 O man, He has told you what is good. What does the Lord ask of you but to do what is fair and to love kindness, and to walk without pride with your God? (NLV)
Why do some attempt to put holiness living in a negative light? Certainly, it is part of the spiritual warfare going on in the world. Those who follow Christ rather than the world - that just isn't "cool." In the event this maneuver proves ineffective, accusations of elitism and self-righteousness may ensue. When all else fails, any flaws and failures must be discovered and exploited.
Living a life of holiness can make one a target. Unless one lives a life of solitude and is not engaging the world, the likelihood of experiencing one or all of these attacks is inevitable.
How can these tactics be so useful? Because to a greater or lesser degree, We are vulnerable to each one. Any one of them could be true. Regardless of whether or not we have decided to follow Christ, we are born with a sin nature. To deny it is to declare God a liar.
When we seek the approval of others instead of God, the mocking may be effective in leading us off the path of holiness. If we maintain a holy life is it because we have never experienced any significant challenge to it? If we're not careful, we could fall victim to a prideful attitude. If we have escaped that particular snare but are not mindful of our demeanor, others could still perceive us to be self-righteous. Lastly, the ugly fact is that we all do have failures - maybe even skeletons in our closets. Any one of which could be selected and used against us.
In Christ, our sins cannot condemn us. We must, however, be mindful that our actions reflect on Him and the body of Christ.
Romans 5:1 Therefore, since we have been justified by faith, we have peace with God through our Lord Jesus Christ. (ESV)