It can make one more prone to seek and grasp and keep power. Rather than knowing and accepting that value comes from God, and one can only be fit for ministry through God's grace, one seeks to prove oneself worthy through effort, through proving to others how good you are at the job, how worthy you are of it, how much they ought to respect you for it. It can, alternatively or simultaneously, cripple one's decision-making faculties; it becomes impossible to push forward on projects, to face opposition, to set a clear course, because all of those involve the risk of your imposter status being exposed.
Fundamentally, when negatively construed, the Imposter Syndrome convinces one of one's own deep unacceptability and unacceptance relating to other people. The constant need to keep one's head above water is exhausting and cripples any ability to move forward in ministry for the purpose of the Gospel. But here is liberating news: you are, I am, a complete imposter when it comes to the ministry.
Frankly, we're imposters if we think we are really functioning, acceptable humans. “There is no health in us”. We can allow our deep sense of inadequacy gnaw at us and make us destructive or incapable, thereby harming anyone we minister to or with. Alternatively, we can embrace that inadequacy – confess it, shout it loud from the rooftops, and have a ministry based on our inadequacy... but God's supreme adequacy, which is all that qualifies any Christian for our faith. God's grace is precisely for the inadequate and broken; it is what fixes us and makes us able to be what we were first created to be. Christians in ministry have no reason to put up a hard exterior or pretend to be sorted. The very truth we preach and the very counsel we give revolves around the fallen nature of Man – and the glorious redemption available in Christ.
I have been and will be practising this discipline – the discipline of embracing my Imposter Syndrome, knowing that Christ offers the only solution to it – and already see fruit in it. I commend it to you.