If Jesus was not born of a virgin;
If Jesus did not perform miracles exactly as described in the Bible;
If Jesus did not return on the third day in the flesh;
If the statements in the Bible about these things are not true;
If Jesus was not divine (this follows from the above, since none of the above are hard to accept as the achievements of a divine being);
Then Jesus was not the Son of God (he was a con-man);
Then the New Testament is worthless as a statement of historical and religious fact.
This should leave you with the conclusion that the Jewish or Muslim faiths may be the true faiths; you cannot call yourself Christian;

But, if the New Testament is worthless;
Then, since the Old Testament is peppered with overt and hidden references and prophecies to the coming of Jesus including the exact location (Micah) and time (Daniel) of his birth;
You must doubt the Old Testament also.
And if you don’t feel comfortable
with the Son of God,
You are but a short way to doubting the Father.

If you believe in Cod the creator (regardless of whether his methods were in the semantics of Genesis or more in line with Stephen Hawking);
If you therefore accept his divinity (= power beyond our understanding);
If you believe he gave us free will;
If you accept we used it for good and evil,
and that He decided to take action:
to send his Son to live among us to show us
the Way, and to make the supreme sacrifice to redeem our sins;
And even if you only believe that God's son is as much as could be poured into human form, as long as that includes his divinity;
then you will have no difficulty believing the virgin birth, His power to heal, to prophesy, to die for our redemption.
And it’s then an easy thing to believe He rose again in the flesh, and appeared physically to his many followers, including Thomas, and the disciples on the road to Emmaus.
And you can also easily accept the power of the Holy Spirit, who at Pentecost so inspired the apostles, that their message has reached 1.3 billion today.
You may have come to these beliefs through an event or series of events when you were "born again" in Christ.

If you believe these things, and you live your life in compatibility with it, with deeds that reflect your beliefs, you will be a beacon to those around you, and you will have no difficulty telling them the good news of Jesus, and you will truly be able to call yourself a Christian.