Open theism may help conceal deep idolatry in the soul. One of the great needs of our souls is to know if we treasure anything on earth more than we treasure Christ. Treasuring anyone or anything more than Christ is idolatry. Paul said in Colossians 3:5, "Put to death therefore what is earthly in you . . . covetousness, which is idolatry." If covetousness is idolatry, then desiring earthly things more than we desire God is idolatry. That means we must be more satisfied in Christ and his wisdom than we are in all our relationships and accomplishments and possessions on earth.
All of life is meant to be lived to reflect the infinite value of Christ (Philippians 1:20). We show his infinite worth by treasuring him above all things and all persons. Believing in his all-ruling, all-wise sovereignty helps reveal our idolatries in times of pain and loss. Not believing that God has a wise purpose for every event helps conceal our idolatries. Thus Open Theism, against all its conscious designs, tends to undermine a means of grace that our deceptive hearts need.
(for full article see http://www.desiringgod.org/library/fresh_words/2002/041002.html)