Paul seems to be pretty clear that the ends do not justify the means in Romans 3.
And as far as missionaries doing evil to win souls... well, that generally doesn't work out too well over the long haul. I remember having a bird with the Campus Crusade guys over this many decades ago. The light of Jesus eventually illuminates the darkness... and a lot of their so called works were for naught, as you can't build a lasting foundation on sand. Granted, all these years and deconverts later, the say, well those deconverted folks were never Christians in the first place, cause of OSAS... sure.
The thing is, very little is black and white, most situations are filled with grey.
Consider the Roman Centurian... who was a man under govt authority, and had to do what his superiors asked. Jesus never told him to quit his job, but rather marveled at the man's great faith. He didn't even tell him to go and sin no more, but rather he told him his servant would be healed. And from what we know about Roman govt practices, it was not exactly on the up and up... and yet Jesus said nothing. Romans 13 can be instructive in this.
A person can be Christian, a church or ministry can be Christian, but a govt cannot. An individual Christian is under the authority of Jesus words on the Sermon on the mount, where as the same Christian, acting under govt authority as a soldier or police officer could be commanded to do things totally opposite of the sermon on the mount. This is not always an easy thing to reconcile.
A Christian friend is working to counter international sex trafficking. He see's these little kids in houses or prostitution, and wants to rescue them right now, especially as he thinks of his daughter who is the same age back home. Yet, he also realizes that in doing so, he might be able to save an individual, but the lives of tens or even hundreds would be put at risk. He is a guru at being deceptive, and has saved countless lives over the years... but unlike the Campus Crusade folks, he is acting under the authority of the state. Its grey, its very different... lots of folks cannot do the type of work he is involved with.