Romans 10:10 For with the heart one believes and is justified, and with the mouth one confesses and is saved.
Conversion is both an event and a process. It occurs, but it continues occurring throughout the life of a Christian. It had divine action as well as human response. Conversion is a sign of, but not the condition of, our justification. We have to be given grace in order to repent and be converted. We can’t obtain our own salvation just through choosing to believe. The power to believe is given through the grace of God and regeneration takes place before we can have faith.
Of all the aspects to the salvation process, this is the first that requires any action of the person; all work up to this point has been done (mostly in secret) by the Holy Spirit in the heart of the regenerate person. Now comes the time to respond to the call. Just to be clear, we must respond but we are not responsible for our own salvation or conversion. Only after we have had a work done in us by God can we even conceive of making the move to respond.
This is the part you may know as “accepting Jesus as your Lord and Savior”. The important part here is the acceptance of Him as Lord. An acknowledgement of the need for a Savior is not the same as turning your life over to Christ. Responding to the call of God with repentance and surrender is the beginning of the life-long process of sanctification.