John 10.28 is a verse not only of great comfort but one that teaches us to live life with a certain expectation. We read I give them (my sheep) eternal life and they shall never perish; no one can snatch them out of my hand.
The great comfort is easy to spot - the promise of eternal life and never perish. What a great God! But before we meet our Father in glory, the believer must live the Christian life knowing that he or she is on Satan's hit list. They are a target as Satan and his demonic forces come to visit you, your family, your life, seeking to "snatch" you from the Father's hand.
Jesus is teaching His disciples to live a balanced life - one which has the believer's feet firmly planted in the promises of God and at the same time aware of the vicious, subtle attacks. Do you know you are under attack? That when you repented and put your faith in Jesus, you were put on Satan's hit list? This awareness will spur us on to rely on God's great promises as well as live with great boldness. Satan may attack but God will prevail as the victory has been won for God's people.