We state our position on this in This We Believe (IV, 9): “We reject the teaching that believers can never fall from faith (‘once saved, always saved’), because the Bible says it is possible for believers to fall from faith (1 Corinthians 10:12).”
In addition to the Bible verse listed, we could add Luke 8:13; Galatians 5:4; 1 Timothy 1:19; and, 2 Peter 3:17-18.
Those verses warn against self-confidence and the possibility of falling away from faith. We take those verses seriously. At the same time we cling to our God’s promise that he will guard and protect our faith to the end (John 10:28).