No, you can't be a Christian unless you have asked Jesus Christ to be your saviour and Lord of your life. It's that easy.
Only a minority of Christians would say this, in itself, is definitional of Christianity.
It specifically contradicts the beliefs of the Catholic, Orthodox, Anglican, Lutheran and Reformed churches - which uniformly hold that an objective acknowledgment of Christ's Godhead and His position as the Son in the Trinity are essential for Christian belief as well (they would also insist on baptism, at least minimally as a sign, for inclusion in the Church).
For example, I have known people who acknowledge Christ as their savior and their lord, but see him as a man placed by God in that role. I think such individuals are definitionally excluded from Christianity.