It's ludicrous that Reverand Alden would believe he was somehow going against God by taking a wife. Hello, he's a PROTESTANT minister not Catholic. In real life, Reverand Alden was a circuit-preacher of the Congregationalist denomination who married twice and sired large numbers of children by each wife (one daughter, in particular, was a good friend of Laura's, as indicated in Laura Ingalls Wilder's books).
Reply: Even though Protestant ministers are permitted to marry, that doesn't mean the ministers don't sometimes fear that they are "going against God." Marriage is a huge undertaking for anyone, and a married minister would not be devoting his entire livelihood to God in the same way he would if he remained single. If you watch the episode, that's why Harriet's former fiance (also a minister) broke off the engagement: because he didn't feel he could properly serve both God and a wife.