There are always two spirits at work: the Holy Ghost and a satanic or false spirit. Witchcraft comes from a satanic spirit and opposes God's Spirit.
There are issues in which believers will disagree. In such cases, we should understand that we will independently stand before the judgment seat of Christ.
Men rob God by simply withholding what God requested. This robbing takes on two forms: not giving what God has required or giving less than one’s best.
How would making your motive match the Lord's motive change how you approach the Christian life (from witnessing to praying to Bible reading and so on)?