The same question was asked by a frustrated jailer in Acts 16:30. We find the answer in the following verse, "Believe on the Lord Jesus Christ and you shall be saved - you and your household" {Acts 16:31}.
The word 'believe' , as it is used here, is not refering to merely 'head knowledge' but to the act of 'completely putting ones trust in'. Therefore, it is not enough to know about Jesus, or know that He is the Saviour. We must put our trust in Him and the finished work that He performed on the cross. {John 3:16}
Salvation involves the confession of sin to God. In 1John 1:9 it says, "If we confess our sins He is faithful and just to forgive our sins and cleanse from all unrighteousness". Romans 10:9 reads, "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."
Salvation also involves repentance. The word 'repentance' means 'to forsake' or 'to turn around'. Therefore, we are expected [with God's help] to turn our backs on everything that is contrary to the word of God. {2 Pet 3:9}
Sincere 'confession' and 'repentance' [what is known as being saved] is the beginning of a relationship with God. Salvation is not about rules, it is about a relationship. Just like a human relationship our relationship with God must be maintained or it will grow cold and joyless. {John 15:5}