Colossians 1:3-4

We continually give thanks to God the Father of our Lord Jesus Christ (the Messiah), as we are praying for you, For we have heard of your faith in Christ Jesus the leaning of your entire human personality on Him in absolute trust and confidence in His power, wisdom, and goodness] and of the love which you [have and show] for all the saints (God’s consecrated ones), Colossians 1:3-4

Therefore He is able also to save to the uttermost (completely, perfectly, finally, and for all time and eternity) those who come to God through Him, since He is always living to make petition to God and intercede with Him and intervene for them. Hebrews 7:25

The Truth that allows us to have complete and absolute confidence is that Jesus never stops, not for one second, interceding for us. He knows that we are going to mess up and yet that doesn’t stop Him from making sure that we are saved to the uttermost.

In conclusion, be strong in the Lord [be empowered through your union with Him]; draw your strength from Him [that strength which His boundless might provides]. Ephesians 6:10

Yet the Lord is faithful, and He will strengthen [you] and set you on a firm foundation and guard you from the evil [one].  2 Thessalonians 3:3

Now may the Lord of peace Himself grant you His peace (the peace of His kingdom) at all times and in all ways [under all circumstances and conditions, whatever comes]. The Lord [be] with you all. 2 Thessalonians 3:16

Another Truth that allows us to have complete confidence in God is that we do not have to rely on ourselves. We draw our strength from our Father. We do not look to ourselves and it is Jesus, Who ever lives to intercede for us, that gives us peace.

Now to Him Who is able to keep you without stumbling or slipping or falling, and to present [you] unblemished (blameless and faultless) before the presence of His glory in triumphant joy and exultation [with unspeakable, ecstatic delight]-- To the one only God, our Savior through Jesus Christ our Lord, be glory (splendor), majesty, might and dominion, and power and authority, before all time and now and forever (unto all the ages of eternity). Amen (so be it). Jude 24-25 

Jesus intercedes for us so that we are saved to the uttermost. Jesus is the One Who keeps us from stumbling. Jesus presents us unblemished and faultless. We can have complete confidence because we never have to rely on ourselves. We are able to cast all of our cares, fears, doubts, questions, and shortcomings on Jesus.