Most church going married men would not buy porno and leave it on their bedroom dresser for their wife to find.
Many, many church going married men are into a great deal more than just buying porn. Some like the former governor of New York, spend thousands of dollars on a high priced hooker. Others, like the Idaho senator, play footsie in a public men's room. Some chase teenage choir girls. Others do worse.
If you have children in the house, and he has left this out, that was not smart at all. No kids in the house, then as others have mentioned, he may telling you something about spicing up your relationship.
Your mother-in-law may not have realized what was in the magazine.
Your husband is not evil because he looked at a magazine with some porn in it. It's a rare, all most not existent, guy who won't take a peep.
A straight forward non-agrumentative conversation with husband is the best thing you can do.
