Take a look at what Jesus said about hypocritical leaders. Take a look at Paul's about how hypocritical leaders can bring demonic influence which bring demonic teachings that will lead people away from the faith. That should all be pretty clear, they're both using the same Greek work: hipokrisis.
The whole matter is about submission and authority. If Christians submit themselves to the influence of insincere leaders, they can come under demonic deception. Moreover, when you submit to someone's authority, they now have permission to pray into, over, and about you in the spiritual realms. That can be powerful for God's Kingdom, or it can be abused for wicked means.
Insincere leaders can use witchcraft to manipulate the way the people under their authority think and act. Witchcraft is simply praying willful prayers which are not lined up with Father God's will.
The deeper you submit to such leaders, the stronger the control they have over you because praying can be powerful in good and bad ways.
For example, a stable Biblically sound mainstream evangelical church can begin to use Jesus Culture songs in their praise and worship to appeal to young people (a seemingly harmless thing to do). This kind of decision, however, puts the people in that church under a measure of influence of the ministry of Bethel Church. You can bet Bethel is praying over their ministries, and you can bet those prayers are manipulative and unleash foul spiritual forces against those who carelessly come under their influence.
Pretty soon, the young people who grew up stable in the faith begin to look into Jesus Culture and buy their music, submitting at an even greater level. As they open themselves up to such influences, they are drawn deeper and deeper into the snares of their control. Before long, they are buying the books put out by these ministries which are not grounded in Biblical truth, but are born of demonic deception. If one is not careful, they may end up attending a school of ministry.
How utilizing witchcraft? Just watch the movie Holy Ghost. You see very clear examples of their ministry teams on the street drawing people to submit to the things they are saying. As they draw them deeper into submission, the foul spiritual forces behind them begin to manifest.
It starts with a hello, then talking to the person about spiritual things, then asking of they can lay hands on them, then telling them to do something like hold their hand out. All the while, the unwitting person is submitting themselves to their authority. By the end of it, the person has some physical sensation like goosebumps, or tingles, or an alleged healing. They're astonished at it, but what was the purpose? The gospel isn't preached. They're basically leading people into a fleshly experience and then tacking on Jesus' name to it.
There is a movie called "Holy Ghost Exposed" on youtube. Watch it and you will see what I mean.
Moreover, there is a huge pyramid structure built on this submission and authority model which is not unlike the Catholic church. It's very deceptive and growing by the day. It may be the strong delusion Paul warned of.