"Keep yourselves in God's love as you wait for the mercy of our Lord Jesus Christ to bring you eternal life." NIV translation
At first glance, this verse may be confusing as we say to ourselves that we cannot get out of God's love. Although it is true that you cannot do anything that will keep God from loving you (because God is love), you can get to where you cannot feel God's presence and therefore His love. You will not feel God's presence/love when you are not walking the talk. Simply put: If you want to be ready for the battle, do not only read the word and pray (as we saw in verse 20) but also put the word into action in your own life. The first thing the enemy will try to do is to get some separation between you and God and that is usually achieved when we are not following God's word.
"Be merciful to those who doubt; snatch others from the fire and save them; to others show mercy, mixed with fear - hating even the clothing stained by corrupted flesh." NIV translation
Jude gives us instructions here for dealing with three different groups of people. The first are those that are Christians but are not strong in their faith. We are to be merciful to them and that means helping to build them up and not beating them down because of their doubts.
The second group are the unsaved that God is calling to himself. We are to "snatch" them from the very fires of hell by sharing the Word of God with them. The last group are those that are unsaved and content with their situation. We are to love them but to hate their actions that do not bring glory to God. We are to tell them of the coming judgment and to love them but not let their sins influence us.
"To him who is able to keep you from falling and to present you before his glorious presence without fault and with great joy - to the only God our Savior be glory, majesty, power and authority, through Jesus Christ our Lord, before all ages, now and forevermore! Amen." NIV translation
Jude closes this letter with a prayer and in this prayer is a reminder. He reminds us that Jesus is the way that we will stay strong in the faith. He is the one that can keep us from falling and it is in His power that we stand.