Church at Brook Hills Senior Pastor David Platt is leaving to become head of the International Mission Board, the church announced Wednesday.  The board coordinates missionary activities of the Southern Baptist Convention.  The church says it's sad to see Platt leave, but wholeheartedly supports his decision.  In a video message, Platt said "God has taken [wife] Heather and me on a journey, where He has made it abundantly clear that He's leading us into a role, where I might give more concentrated time, energy and resources ... to see Christ preached where he's not been named."  Platt is expected to take on his new role in about a month.