Name the false choice. The argument assumes only two options: a good, powerful God would prevent all suffering, or there's no such God. A third option is that God has good reasons to allow suffering for a time, even if we can't see them all.
Notice the hidden comparison. It treats love as the absence of hardship. Good parents allow children to face pain for their growth and protection. Love and suffering can exist together.
Point to the cross. Christianity doesn't say God stays distant from suffering. In Jesus, God entered it, and He promises to end it (Revelation 21:4).
Be gentle. This question often comes from real pain. Sometimes the first answer is to listen and grieve with them (Romans 12:15).