"In order to have faith, we must know certain facts about ourselves and about Jesus, who he is what he has done for us. Thus the Apostle Paul asks rhetorically, 'How are they to believe in him whom they have never heard?' (Romans 10:14). You cannot believe in something you know nothing about. Saving faith must have an object. You don't just believe, you believe something. And throughout Scriptures we find essential truths that must be believed. Paul writes that we are saved through 'belief in the truth'(2 Thessalonians 2:13). There are certain doctrines people must hear, understand, and affirm if they want to become true Christians."
Citation: Am I Really a Christian? (By; Mike McKinley; Crossway, 2011)
It's not just I believe! What do you believe and whom do you believe in?