Only one place separated the sides before kick-off with a place in the play-offs still up for grabs but the Atoms could not quite replicate the excellent form that had seen them turn over top-three sides Haydock and Clock Face Miners on consecutive weekends.
It was the Atoms who cracked first, conceding a try as their left defence was given a severe examination.
It only took two minutes for the Atoms to respond as hooker Billy Livingstone darted under the posts after splitting the markers from the dummy half position.
Shevington then clinically finished off a move to give the Wigan side a 12-6 lead as time was running out in the half.
In the first period of the second half Shevington showed some class with two slick moves involving quality offloads giving the Wigan side 12 further points and a nice cushion at 24-6.
Shevington made it 30-6 as the Atoms fell for a dummy close to the line before Al Crookall made a big charge for the line and Liam Hall finished off the move in typical fashion.
Dan Helme and Livingstone targeted the short side and a flick pass from the hooker then brought the strong running centre Jack Edmondson his first try of the afternoon.
It was now 30-16 with 15 minutes remaining and the game was back in the balance.
However, Shevington lifted themselves and scored from what looked like an obstruction try before Edmondson scored his 23rd try of the season, rounding off an Atoms attack that swept from right to left.
The versatile Jake Harrison cut back inside from the right wing and made a half break and Edmondson went over for his hat-trick, only to be brought back for an infringement.
Shevington scored the final try of the game with one minute remaining and booked their place in the top four play- offs, rounding off a great advert for the game at this level.