The answer to that question is not one we are supposed to judge people by. Sure there are Hardened Criminals who will never choose to change their ways and sure there are those mentally ill inmates who may or may not be beyond all help. But we are Children of the Most High and we have been told to take care of the Needy, the Helpless, the Poor, the Widow, the Children and on and on and on.
Since we are told to be Wise as Serpents and Gentle as Doves, we who are trained up in the Ways of YHWH, have no excuse for not being able to work with inmates in prisons and do so in corretness.
We must also remember that we were told by Messiah that what ever we did or did not do for the Least (Meaning Inmates as well), we did or did not do these things for Him. Makes you wonder what He was talking about does it not.
The Kingdom of Heaven is made up of Givers and Lovers. What that means is that a True Believer WORKS on learning how to GIVE rather then Receive and WORKS on understanding the millions of definitions of LOVE while never forgetting the most important definition. This definition was Spoken by the YHWH as the Father and YASHUA as the Son and it is as follows: "If you LOVE me, keep my commandments.
Prison Ministy is one of many ministries a believer can get involved in. To choose to not to get involved in any ministries is to choose to ignore the Commandments of YHWH.