Encourage muslims to leave Islam? Good luck with that. They kill people (and their families) that leave Islam. Islam spreads by the sword. It always has.
Some Zanadiqa (atheists) were brought to 'Ali and he burnt them. The news of this event, reached Ibn 'Abbas who said, "If I had been in his place, I would not have burnt them, as Allah's Apostle forbade it, saying, 'Do not punish anybody with Allah's punishment (fire).' I would have killed them according to the statement of Allah's Apostle, 'Whoever changed his Islamic religion, then kill him.'"
That is why anytime a person leaves Islam, and in a special way, to become a Christian believer it has to be done very, very quiet.