True, but he never gives in to the devil. We have all experienced "low" moments in our faith, and have often felt that the Spirit has "forsaken" us. Even Christ, in His human nature, repeats that on the Cross, about God abandoning Him. Does that mean that Jesus sinned?
When He asked the Father if it would be possible to pass the cup that was awaiting Jesus, was He losing faith and trust?
No! He is showing us that in adversity it is much more difficult for a human being to persevere then when things are going hunky-dory. It's easy to bless God and thank Him for His gifts; but how do we react when things begin to go haywire? Do not so many Christians protest "I am a Christian, I go to church every Sunday, I do charity; how could God allow this to happen to me?" You bet!
The bottom line is that Job wavered, as would be expected, but never crossed the threshold.