Our salvation was guaranteed before Creation--
Ephesians 1:4-5 (NLT) 4 Even before he made the world, God loved us and chose us in Christ to be holy and without fault in his eyes. 5 God decided in advance to adopt us into his own family by bringing us to himself through Jesus Christ. This is what he wanted to do, and it gave him great pleasure.
Assurance comes from faith--
Ephesians 3:12 (NLT) Because of Christ and our faith in him, we can now come boldly and confidently into God’s presence.
God will guard what has been entrusted to him--
2 Timothy 1:12 (NLT) That is why I am suffering here in prison. But I am not ashamed of it, for I know the one in whom I trust, and I am sure that he is able to guard what I have entrusted to him until the day of his return.
"It is not your hold of Christ that saves you, but his hold of you!"--Charles Haddon Spurgeon (1834-1892)
