I don't think you understand how suicidal many LGBT people are.Just say I'm not down with lgbt and move on. Couching your hatred in "im worried about children" is not being direct, there are other questions that can come from that which mainly leads back to the person saying this is attracted to the same sex on some level.
If you are direct we can at least say its out of disgust and go from our disagreement from there but anti lgbtq people hide behind children to make their hatred seem more miserable.
You can't just speak your mind to them.