By "proper" I meant sufficient as an earthly end. You're using "proper" in relation to the time in question. In that sense, yes, the Jews did indeed have a proper sense of God for their time in salvation history (or at least those few Jews who responded dutifully and devoutly to God's call).
Still, no. The Church, whether in OT or NT times, has always had a proper and sufficient conception of God. You say yourself that you mean proper as sufficient for earthly ends, thus you speak of creatures, who live in time. You can not speak of earthly creatures, and take them out of the context of time, in this case, because all of us on earth are in that time. Only those in Heaven and God are outside of time, and we are obviously not speaking of that kind of knowledge.
Think about it this way. Let us say that a theologian arises in 2200 AD, and reconciles all that was good with "modern philosophy" with schasticism and good Catholic doctrine. Then the waltys of the future might claim that God could not be properly understood until this new saint had arisen. To say that would mean that the body of doctrine was not developed properly or sufficiently for it's earthly ends at any given time in it's development
, which is false, and I would hold, sinful to pertinaciously believe. You can not divorce earthly sufficiency and properness from time and circumstance, all of which are created and ordained by God.
That is indeed what I am saying. The earthly end of theology and an understanding of God is salvation. In a very real way, salvation could not be had until Christ had come to earth and we were given the proper understanding and chance to reject or accept Him. Only then did our covenant with God reach its completion. And even then, our understanding of how this all works did not become totally clear until the works of the Angelic Doctor and the Council of Trent. Before that the Church was still trying to figure out fundamental doctrine like Christology and ecclesiology.
I think we may be saying the same thing. Let me put it another way. The knowledge of God given to mankind at any given time has been sufficient and fitting for that time, but it all leads to its culmination and completion in the Incarnation and the subsequent unpacking of that great Mystery. So when I say "proper" I mean that state which God has originally intended mankind to reach in its understanding of who God is.