And, "If it is hard for the righteous to be saved, what will become of the ungodly and the sinner?" – 1 Peter 4:18These passages indicate that we must persevere; we must work out our salvation with fear and trembling; we must finish the race; we must daily die to self and live for God. Why, because Peter makes it very clear that we can fall from our salvation. We can walk away by word or by deed.
Therefore, my brothers, be all the more eager to make your calling and election sure. For if you do these things, you will never fall, and you will receive a rich welcome into the eternal kingdom of our Lord and Savior Jesus Christ. – 2 Peter 1:10-11
If they have escaped the corruption of the world by knowing our Lord and Savior Jesus Christ and are again entangled in it and overcome, they are worse off at the end than they were at the beginning. It would have been better for them not to have known the way of righteousness, than to have known it and then to turn their backs on the sacred command that was passed on to them. – 2 Peter 2:20-21
Therefore, dear friends, since you already know this, be on your guard so that you may not be carried away by the error of lawless men and fall from your secure position. - 2 Peter 3:17
Does this mean that we need to doubt our salvation? No, but we must not take it for granted and we must daily live in a place of repentance so that we are continuing to love God with all of our heart, mind, soul, and strength. We must seriously pursue God everyday so that the world will have no appeal to us.