You are correct, but to me, I'd rather a person stay a certain religion they know and most probably has some sort of link to a Messenger from God originally, then become of a victim of the clergy of Muslims with dwarfed understanding. It's like taking a person out the fire into the frying pan.
If you going to believe in slavery, etc, coming to Islam, maybe it's better a person stays atheist and a Deist for example.
I remember I was sort of dating this woman at university (we never touched, just had food and hanged out) and she asked me for a good translation of Quran, I told her I don't know of any that are not severely distorted in translation. She was horrified, and I told her it's not her fault really. I know most people would prey on people to come to Islam, but, this all I could do, is tell her we've severely misinterpreted Quran so she doesn't disbelieve when reading a Quran translation.
Of course, if a person comes to Quran and Sunnah and reflects, it will heal them. But most people come and then are devoured by our sectarian strife and leaders who are not appointed by God lead them astray.