Well, we can keep going over these same verses again and again, but it's pretty pointless. I'll speak to this one. Look at what Paul has already said in this letter. It most certainly is NOT about working for salvation. :sigh:
Paul is speaking of the obedience of faith.....believing and trusting in God.
Phil. 1:6 Being confident of this very thing, that he which hath begun a good work in you will perform it until the day of Jesus Christ:
Phil. 1:9 And this I pray, that your love may abound yet more and more in knowledge and in all judgment; 10 That ye may approve things that are excellent; that ye may be sincere and without offence till the day of Christ. 11 Being filled with the fruits of righteousness, which are by Jesus Christ, unto the glory and praise of God.
Phil. 2:13 For it is God which worketh in you both to will and to do of his good pleasure.
Here again....the obedience of faith....believing.
2 Thessalonians 1:8 He will punish those who do not know God and do not obey the gospel of our Lord Jesus.
There are many things a believer does that can't be called "good", but we don't get saved by doing good, and we don't stay saved by doing good. We are saved by trusting and believing, and we stay saved because He is faithful even when we are not. Be confident in HIM...trust in HIM. That is the obedience of faith.