Romans 10:9-10 says, "If you confess with your mouth, 'Jesus is Lord,' and believe in your heart that God raised him from the dead, you will be saved. One believes with the heart, resulting in righteousness, and one confesses with the mouth, resulting in salvation."
The Bible tells us that in order for us to accept the gift of salvation, we must confess that we believe Jesus is Lord and believe that God raised Him from the dead so that we could be forgiven and saved from our sinful lives. However, it isn't just the words we say, but the belief in our heart and commitment to obey Jesus as Lord. If your child has done that and you believe they are fully aware of what this decision means, baptism is typically a great next step of faith!