Be saved and sure by faith in our Lord Jesus Christ. God's salvation is simple, plain, and clear. Believe and confess your faith in God the Son, our Lord Jesus Christ. If you confess with your mouth the Lord Jesus and believe in your heart that God raised Him from the dead, you will be saved (Romans 10:9).
God gives us the assurance of our salvation (2 Peter 1:10). In the Bible it is made sure and clear. The Holy Spirit will give you the assurance of salvation, as you confess, Jesus is Lord. The Spirit Himself bears witness with our spirit that we are children of God (Romans 8:16). Confess your faith in the Lord Jesus Christ.
You can only believe in your heart when the Holy Spirit does something within you. No one can say Jesus is Lord except by the Holy Spirit (1 Corinthians 12:3). The Holy Spirit leads you to believe in the resurrection of Jesus Christ. He is Lord, which means Jesus is risen from the dead.
With your mouth, confess what is in your heart. The word confess means to speak the same thing. You speak the same thing that is in God's word, that which the Holy Spirit has worked in your heart. Your confession that Jesus is Lord agrees with the Spirit of God and the word of God. Confess your faith in the Lord Jesus Christ. Be saved and sure by faith in Christ.