"Whoever is not against us is for us," Mark 9:40.
Hmm. But Jesus also says: Whoever isn't with me is against me. Which is it? Both. Different contexts. When people with incomplete knowledge of Jesus still do good work in Jesus' name, obviously, they're for him, not against him. Jesus says: Don't stop them. Kind of like Apollos who preached Jesus powerfully but didn't understand baptism into Christ. Priscilla and Aquila nurture him more fully in the Lord's way, and Apollos preaches on. Like, Moses' instruction to Joshua, God's Spirit empowers whom He may, don't shush them. In clear distinction to that, when people claim Jesus' power comes from demons, they're against him. Of these who so blaspheme the Holy Spirit, Jesus says: Guilty of eternal sin, they never have forgiveness. So. God works in unimagined ways pre-preparing and re-repairing hearts, readying men and women to hear the saving Word.
With a brother or sister today, as we open the Word of the cross to despairing hearts, we merge into God's relentless endeavor. And, together, we praise God who counts our imperfect field work as being for him.