When Christians resort to "no one's perfect" in discussing holy conduct, in my experience, they are always making room for failure, for moral and spiritual compromise, and in doing so "conceding the field" to sin. It seems to me far more biblical to say, "By God's grace, I'll live as holy and as Christ-centered a life as the Spirit enables me to do."
Imagine an Olympic athlete at the starting line of the 100-meter-dash who is thinking to himself, "No one wins every race," or "It's inevitable that I'll lose some of my races." Does such thinking aid his race? Does it make it more likely that he'll win when, before the race has happened, he is already preparing himself not to be the winner? Obviously not. How keen, though, Christians are to do this very sort of thing in "running the race" of Christian living! In the way they talk about sin, they seem deathly afraid to believe that sin can become the exception in their life rather than the rule it usually is. They aren't anything like John, or Paul, or Peter in this:
Romans 6:1-2
1 What shall we say then? Are we to continue in sin so that grace may increase?
2 May it never be! How shall we who died to sin still live in it?
Romans 6:6-7
6 knowing this, that our old self was crucified with Him, in order that our body of sin might be done away with, so that we would no longer be slaves to sin;
7 for he who has died is freed from sin.
Romans 6:11-12
11 Even so consider yourselves to be dead to sin, but alive to God in Christ Jesus.
12 Therefore do not let sin reign in your mortal body so that you obey its lusts,
1 John 2:3-6
3 By this we know that we have come to know Him, if we keep His commandments.
4 The one who says, "I have come to know Him," and does not keep His commandments, is a liar, and the truth is not in him;
5 but whoever keeps His word, in him the love of God has truly been perfected. By this we know that we are in Him:
6 the one who says he abides in Him ought himself to walk in the same manner as He walked.
1 Peter 1:14-16
14 As obedient children, do not be conformed to the former lusts which were yours in your ignorance,
15 but like the Holy One who called you, be holy yourselves also in all your behavior;
16 because it is written, "YOU SHALL BE HOLY, FOR I AM HOLY."
2 Peter 3:10-11
10 But the day of the Lord will come like a thief, in which the heavens will pass away with a roar and the elements will be destroyed with intense heat, and the earth and its works will be burned up.
11 Since all these things are to be destroyed in this way, what sort of people ought you to be in holy conduct and godliness,
Galatians 5:16
16 But I say, walk by the Spirit, and you will not carry out the desire of the flesh.
Galatians 5:22-25
22 But the fruit of the Spirit is love, joy, peace, patience, kindness, goodness, faithfulness,
23 gentleness, self-control; against such things there is no law.
24 Now those who belong to Christ Jesus have crucified the flesh with its passions and desires.
25 If we live by the Spirit, let us also walk by the Spirit.
Colossians 3:2-5
2 Set your mind on the things above, not on the things that are on earth.
3 For you have died and your life is hidden with Christ in God.
4 When Christ, who is our life, is revealed, then you also will be revealed with Him in glory.
5 Therefore consider the members of your earthly body as dead to immorality, impurity, passion, evil desire, and greed, which amounts to idolatry.