You ask why rational people try to engage theists into critical thinking, then go on to detail how you, like most atheists, began as a child being conditioned to believe the theist myths of your parents until you discovered the skills of critical thinking and objective reasoning.
So you prove that theists can break their conditioning but then question why we bother trying to free the minds of others who, like us once, were brainwashed.
Some Christians are threatened by atheism's rise on the pop charts. Some say atheists "hate God." But of course, a philosophical atheist cannot hate something he does not believe exists. Many atheists, though, do hate religion...
There's no good reason why a Christian should ever be "threatened" by atheism's rise. Saddened maybe, feeling bad for them, yes. But threatened? There's no good reason for that. Christians believe God will be with them forever and they'll go to Heaven, and God will shine His light on them, and bless them. There's nothing to be threatened with when God is with you, who can be against you?
Romans 8:31 What shall we then say to these things? If God be for us, who can be against us?
Perhaps not Christians individually, but certainly a shrinking pool of adherents is threatening to the religion as a whole. The financial base drying up is an existential threat, and a smaller base is less political power as well. Individuals care about converting nonbelievers because they're taught to believe this is necessary (for soul-saving reasons) by the church hierarchy, when it's actually for perseverance of the financial and political power base of the church.