Why is this important? Christ’s identity is central to the gospel. If Christ is not God, Christianity is a sham. Further, there is no hope to be reconciled to God. Yeah it is that important. Your friends, who have bought into other means of reconciliation to God than Christ, are in trouble. This is not about intolerance or coexistence this is about caring for people. If you see a stranger about to step off the curb in front of an oncoming bus, you do not engage them in a debate on the merits of the action, you pull them back. Jude 23 exhorts us to do the same with those who have chosen a wrong path.
Central to that wrong path, is their view of Christ.
By the way those who do not believe Christ is God are not limited to the cults.