The verse is a compound sentence, with subjects, verbs, direct and indirect objects. There is no separate thought.
We should always give thanks to God for you as beloved by the Lord.
Subject, =We; Verb = should give thanks, direct object = God; indirect object for you the beloved.
We should give thanks to God for you as our siblings in Christ!
Why?
Because God has chosen you.
Subject = God; Verb = has chosen; direct object = you.
The remaining phrases are indirect objects describing aspects of the action upon the recipient.
When was the action of choosing performed? From the beginning of the New Covenant
What was the purpose of the action? For salvation
What were the instrumental factors? Through sanctification by the Spirit and faith in the truth.
Election was accomplished by transferring the person from the realm of darkness into Christ.
Basis of the choice was God crediting the faith of the individual as righteousness.
Thus we were NOT saved because of our faith, our faith only allowed God to credit it or not. Our faith did not deserve salvation or merit salvation, the accreditation was a act of mercy and grace. Salvation does NOT depend upon the person who wills, but upon God who has mercy.