II Corinthians 11:13-15
13) For such men are false apostles, deceitful workmen, disguising themselves as apostles of Christ. 14) And no wonder, for even Satan disguises himself as an angel of light. 15) So it is no surprise if his servants, also, disguise themselves as servants of righteousness. Their end will correspond to their deeds.
After many years away, I return to the Lord. Like the oft noted prodigal son, I left the home of my Father to spend time in the world. When the world spat me out, I realized I could yet go home. My Father would not turn me away.
This time, I determined to hold to 2 Timothy and study the Word myself.
2 Timothy 2:15 Study to shew thyself approved unto God, a workman that needeth not to be ashamed, rightly dividing the word of truth.
To be clear, I do not study for justification. Justification is granted the moment you give yourself to Christ. Sanctification is the setting apart. It is the process of yielding to the Holy Spirit and changing to become more like Christ. It is what happens to the believer as he begins to recognize sin in his life, desire to separate himself from sinful behaviors and surroundings, and trusting in God to help him change. It is continual process, and there will be failures.
I am studying on false doctrines, at the moment. I just finished the book Another Jesus Calling 
It seems that everywhere I turn there is a new church springing up. There are new preachers on television claiming to have the answers. Some are “modernizing” their services by incorporating chanting (repetition of verses) and visualization. Each uses Scripture to support his idea of the right way to salvation. This is why we must study in addition to listening to someone preach or teach.
Many preachers sound like they know what they are talking about. They will come like an angel of light. They will “enlighten” you to a “new way” of applying Scripture. Many of these “new ways” entangle the occult, new age, and practices of religions that are not of Christ. This is dangerous to your Christian walk.
Don’t believe me, read the Bible and find out for yourself.