There is an obvious sense in which we can understand that Christianity began with Jesus. But there is another sense in which we must say that Christianity began in the garden of Eden when God responded to humanity’s first sin.
Gen 3:14 The LORD God said to the serpent,
“Because you have done this,
Cursed are you more than all cattle,
And more than every beast of the field;
On your belly you will go,
And dust you will eat
All the days of your life;
Gen 3:15 And I will put enmity
Between you and the woman,
And between your seed and her seed;
He shall bruise you on the head,
And you shall bruise him on the heel.”
This reference to the woman’s seed was the beginning of the messianic hope – though it would be centuries before it would be referred to in that way.
Acts 28:20 – “the hope of Israel”
1 Tim 1:1 – “Christ Jesus who is our hope”
The hope of Israel eventually blossomed into the faith of mankind.
Since the word “Messiah” (from a Hebrew word) and “Christ” (from a Greek word) mean the same thing, Jewish messianism and Christianity should be understood to mean the same thing.
The Duty of a Man 