Picking letters for the Monday Morning Quarterback is always fascinating. And sometimes painful. We asked for comments and we get them.

Except for my introduction (which one reader thinks is a waste of space), the Monday column is written by the readers. If you want to sound off on any federally related subject, we welcome your letters. Keep them as short as possible. This is what some of your friends (and enemies) and neighbors are thinking:

* "Quit being a jerk! Stick to the taxpayers for a change and not with the overinflated and overpaid federal employe. In the March 31 column you said that the Office of Personnel Management Director 'has sent morale to rock bottom.' Nonsense. Let those who don't like it quit. There are many people standing in line for federal jobs. [Actually, the column said that Devine might have trouble being reconfirmed by the Senate because 'many federal workers claim that Devine has sent morale to rock bottom.']

"I dare any federal worker who doesn't like his job or his supervision to quit. However, they won't quit because they are well paid and overpaid and they have it made, and YOU know it!

"The taxpayers are getting a ripoff from the overpayment of federal workers, especially the postal workers who don't even need a high school education. Why don't you quit your column and write something more educational and constructive?" J. from Silver Spring.

* "Your anti-federal worker bias is apparent to all. Everytime you write about a proposed pay or benefit cut, you mention how much it would 'save' the government. Also, you never advise federal workers and retirees who they can write to in the Congress in opposition to cuts in federal pay and retirement. With a 'friend' like you, we surely don't need any more enemies." D.B., Rockville.

* "Your column is the only reason I take the Post. But please, when you have the Monday Morning Quarterback, don't waste one-third of it telling us what we're going to read. If we don't understand what is said, we won't read your column. If we do understand it, your taking so much space explaining it to us is unnecessary. Rather than reading your repetitiousness, you could give us another letter." Constructively yours, B.L., Washington.

* "President Reagan, Agriculture Secretary John Block and company are really going for religion in government. The enclosed flyer announcing Good Friday Easter Services at the Agriculture Department's auditorium was found on every table in the cafeteria.

"For Thanksgiving we had a revivalist in the patio of the Agriculture administration building. Sweet Jesus is wonderful on Sunday, in church. But mid-week missionaries in government buildings are out of place, I think." Ag Dept reader.

* "About smoking in government buildings. I have an allergic reaction to tobacco smoke. That aside, I feel it is irresponsible for the government to condone a practice that is proven injurious to the public health.

"I personally will not attend meetings in rooms where the residue of smoke lingers . . . . I request that people not smoke in my presence, wherever that is. If more non-smokers would speak up it would help. Sheer numbers are convincing. What better place to start than if the federal government would ban smoking on federal property.

"I can't sign my name because our agency director smokes a pipe." NIH employe.