I recall they Jesus was condemned by the Pharisee and Sadducces for eating and speaking with sinners. Can we do no less than to invite them to know the teachings of Jesus? Or should we keep our churches for only us and our fellow non-sinners?
They are welcome to come, but that's different from giving them full voting privileges in the congregation, or putting them into a leadership position.
One Presbyterian theologian marked the fall of the Presbyterian denomination at the date of their last heresy trial. If you have a faith that doesn't define heresy, you don't have much of a defined faith at all.