The main idea that refutes Christ's completeness and wholeness is called Syncretism- a condition where we try to mix what is supposedly perfect on its own with something else to try to add to its value. Surprisingly, syncretism is something that men have struggled with for as long as we can remember. It's still prevalent today and is most certainly the cause of all the problems we face today.
In the book of Galatians, Paul harshly speaks against any attempt to add to the Gospel. He says in Galatians 1:9, "As we have said before, so now I say again: If anyone is preaching to you a gospel contrary to the one you received, let him be accursed." There is one Gospel and nothing more. We do not have to add anything to the finished work of Christ - not works, liberalism, views, concepts, career or anything.
It's very much like drinking coffee. I once worked for a ministry that put up a coffee shop that became a place to reach out to the youth. One of the most important lessons I learned about coffee in that season was that it's perfect on it's own. Coffee in pure bitter form is the way it should be taken, but because people love to sweeten everything, we dump as much sugar into it thinking that's how coffee should be consumed. But all that sugar just distorts the flowery taste and body of your coffee.
Adding to the Gospel works the same way. We try to add to what Christ has done for us thinking that if we read our Bible more, pray more, go to church or avoid certain things that we will gain His favor. There's nothing wrong with doing any of these things. As a matter of fact, we should all do all these things. The problem comes when we think that we are doing all these things to earn salvation or blessing. God doesn't need your help to save your soul. He's already done it on His own.
Deuteronomy 4:2 says "Do not add to what I command you and do not subtract from it, but keep the commands of the LORD your God that I give you." Syncretism is still pretty much alive and we have a problem. It looked way different before (doctrine, religion, practices) but by principle we have the same issue. The way we live all live (including me at times) always stands by the idea that Jesus isn't enough and that we have to add to Him.
When financial struggles happen, suddenly Jesus isn't enough. All of a sudden we need other things for provision. When our reputation and face value is on the line, all of a sudden Jesus isn't the primary and only source of our satisfaction and joy. Do we truly live out a life that professes that Jesus is everything we need? Does the work that we do profess the doctrine that we study?
We need to come to this understanding where when we truly have Jesus, everything else is just an added bonus.
