If you already know the Father, the Son, and the Holy Spirit, then you already know God the Holy Trinity. Of the three, we can relate to Christ the most because he actually did come down to earth to be among us. Through him, you get to know the Father intimately and receive the Holy Spirit. Since God is the truth, when you know him, you just know that he is the true God. How about if you are still seeking God? Know that you are finite and do not know him yet, while he is infinitely greater than you and knows all about you already. So you cannot expect that he would come to you to beg you to believe in him (it's just not appropriate, right?). The right attitude to assume is to believe that he truly exists and go to him humbly to let him know that you desire to know him. Seeing that you are sincere, he will then joyfully reveal himself to you to fulfill all you desire.