"Know ye not that the unrighteous shall not inherit the kingdom of God? Be not deceived: neither fornicators, nor idolaters, nor adulterers, nor effeminate, nor abusers of themselves with mankind,  Nor thieves, nor covetous, nor drunkards, nor revilers, nor extortioners, shall inherit the kingdom of God.  And such were some of you: but ye are washed, but ye are sanctified, but ye are justified in the name of the Lord Jesus, and by the Spirit of our God." 1 Corinthians 6:9-11

Sanctification - set apart for God is positional, progressive and ultimate.

Positionally, it is already complete since the believer is in Christ and set apart unto God. But sadly we are of Adam and therefore retain our sinful nature. So God in His love has also made sanctification progressive. We grow in grace, maturing in faith by the power of the Holy Spirit. Ultimately, the child of God will be set apart from the sin[s] that so easily beset us when we are taken to be with Christ - we shall be like Him.

I heard it said once, we can never let God down, because we do not hold Him up.

God has promised to take care of His children. He will continue the work He has begun in each of us.  Allow Him to chisel, to mold and reshape. Be willing to obey, be willing to follow.

Our righteousness, our sanctification is ongoing. Credited to us.  We must learn to live in the reality of that credit.