Actually, the Holy Trinity is made manifest in the Resurrection (Galatians 1:1, Romans 8:11, +John 2:19).
I really like the New Advent explanation of of the Trinity
http://www.newadvent.org/cathen/15047a.htm#V
Galations 1:
1. Paul an apostle--not from men nor through man, but through Jesus Christ and God the Father, who raised him from the dead-
Romans 8:
11. If the Spirit of him who raised Jesus from the dead dwells in you, he who raised Christ Jesus from the dead will give life to your mortal bodies also through his Spirit which dwells in you.
1 John 2:
19. They went out from us, but they were not of us; for if they had been of us, they would have continued with us; but they went out, that it might be plain that they all are not of us.
How is it made manifest?