You ever read the O.T.?
Gen 18:1 And the LORD appeared unto him in the plains of Mamre: and he sat in the tent door in the heat of the day;
Sounds to me like Abraham knew the Lord. I won't bore you by going through and showing that there were individuals that Christ dealt with, but here is another example...
1Co 10:1 Moreover, brethren, I would not that ye should be ignorant, how that all our fathers were under the cloud, and all passed through the sea;
1Co 10:2 And were all baptized unto Moses in the cloud and in the sea;
1Co 10:3 And did all eat the same spiritual meat;
1Co 10:4 And did all drink the same spiritual drink: for they drank of that spiritual Rock that followed them: and that Rock was Christ.
Hmmm, seems at this time, all of Israel saw Christ.
Exo 20:1 And God spake all these words, saying,
God spoke directly to the people.