I don't think God is "predictable," but I do think He is highly consistent. Take the life of faith, for instance. If I accept God as my creator and Christ as the God-man and my savior and Lord and act accordingly, I will benefit. The world may not appreciate the benefits (although there may be worldly benefits for some, maybe even many, Christians), but I will bear fruit and becoming godly and strong in character, like a tree planted by the river (I forget the address for this paraphrase). If I reject God and do terrible things, like engage in unrestrained sexual immorality and violence, I can expect bad things to happen, usually both on this earth and in the hereafter, but definitely in the hereafter. If I pray, God will listen. If I draw nigh unto God, God will draw nigh unto me.
These things don't indicate "predictability" so much as they show us a glimpse of God's character. Why does God reward the good and punish the wicked? Because He is just and He never changes. Why does God save the outcast and the pariah, 2,000 years after Christ walked the earth? Because God is merciful and "no respecter of persons." We know this because it is in His word and because, once our eyes are opened, we can see it happening all around us. But this isn't "predictability," because God is a mysterious Spirit who has chosen to keep many things to Himself for the time being. His ways are higher than our ways, as D4Christ pointed out.
I think calling God "predictable" seems a bit arrogant, but it could also simply be a case of poor word choice.