Take Jesus, for example; there are few words you can use which don't seem inappropriate. Loving is OK, but friendly is not; understanding is probably just about acceptable, but sympathetic doesn't seem to hit the right note. There's even less you can say about God: he can be all-powerful, merciful, eternal, or just, and there are many other compliments which are perfectly in order, but you could never call him charming, keen, shrewd, cheerful, tidy, clever, sporting or brave.
In fact we've got into a rather tongue-tied state about our gods altogether, considering that medieval theologians used to maintain that God was the sum of all possible perfections. That should have provided plenty to say about him, but they didn't take the opportunity to describe, say, his powers of deduction, command of languages or infinite capacity for hard work.
And quite what's being asserted of God when it's said that he's merciful, etc, it's difficult to know. If one queries whether God is quite as merciful as he is cracked up to be, given the astonishing number of quite merciless things which occur under his jurisdiction, and which in any other organisation would lead to vociferous demands for his resignation, religious people are astonished at the naïvety of one's interpretation.
'Good heavens!' they cry, often laughing cheerfully as well. 'When we say that God's merciful we don't mean that he's merciful in any merely human sense of the word. With our miserably limited understanding and our pathetically inadequate language, we couldn't hope to make anything but the most incomplete and misleading attempt at describing him. There's no way of knowing what we mean when we say that he is merciful. For all we know, God's mercifulness may consist of just those very things which we, with our poor understanding, think of as merciless!'
Gods weren't always as indescribable as this. The Greeks didn't hesitate to characterise their team as lecherous meaning lecherous, jealous meaning jealous and drunken meaning drunken. God is very clearly characterised by the Old Testament too: he invents his laws as he goes along, he insatiably demands flattery, he bullies his courtiers and plays cruel tricks on them, he murders individuals and destroys whole communities who step out of line. Most of the time he is in a vengeful, smiting kind of mood.
Now that's what you might call a God. Nobody could read the Old Testament without being stirred to wholesome indignation. But then it was felt that this didn't reflect the changing tastes of the age and that it might be having an anti-social influence, so they tried to make the chief character turn on goodness instead of sheer power. They stopped him murdering people, and had him helping them in distress instead, though not of his own accord; you still had to ask him nicely.
This is an implausible depiction, and a weaker piece of characterisation; it may go some way to explaining the decline of religion in recent times.
Acknowledgements to Michael Frayn's A Question of Character