Why does Tom begins to go to church and carry a bible around with him all the time

He begins to realize that he has made a huge mistake making his deal with the devil and tries to "redeem" himself by good living and doing what he thinks might be the right actions.

Tom has made a deal with the Devil. Tom knows that the Devil always comes to collect his due. Tom turns to the Church because he is worried about his deal and his afterlife. Tom carries a Bible and goes to Church because he thinks this would thwart the Devil coming to collect from Tom.