Why Preach Faith and Repentance ?
Paul said Acts 20:21
21Testifying both to the Jews, and also to the Greeks, repentance toward God, and faith toward our Lord Jesus Christ.
The word testifying here is the greek word diamartyromai and means:
to testify
a) earnestly, religiously to charge
2) to attest, testify to, solemnly affirm
a) to give solemn testimony to one
b) to confirm a thing by testimony, to testify, cause it to be believed
Notice, it means cause it to be believed !
Remember Paul said to the Thessalonians 2 Thess 1:10
When he shall come to be glorified in his saints, and to be admired in all them that believe (because our testimony among you was believed) in that day.
Was believed is Passive voice, so was caused to believe !
Also, 1 Cor 1:6
Even as the testimony of Christ was confirmed in you:
The Testimony of the Gospel is what was confirmed in them !
The Testimony of the Gospel is made sure in all for whom Christ died, they will be caused to believe it ! That is also what Paul means here 1 Tim 2:6
6Who gave himself a ransom for all, to be testified in due time.
All for whom Christ was a ransomed for, shall have the Testimony of it confirmed in them by the Gospel, the Gospel of their Salvation Eph 1:13
Consequently, this turns them from their idols, to belief in the Truth. 1 Thess 1:4-9
4 Knowing, brethren beloved, your election of God.
5 For our gospel came not unto you in word only, but also in power, and in the Holy Ghost, and in much assurance; as ye know what manner of men we were among you for your sake.
6 And ye became followers of us, and of the Lord, having received the word in much affliction, with joy of the Holy Ghost.
7 So that ye were ensamples to all that believe in Macedonia and Achaia.
8 For from you sounded out the word of the Lord not only in Macedonia and Achaia, but also in every place your faith to God-ward is spread abroad; so that we need not to speak any thing.
9 For they themselves shew of us what manner of entering in we had unto you, and how ye turned to God from idols to serve the living and true God;
Note vs 6 How they received the word with Joy of the Holy Ghost ! That proves they had been born of the Spirit in order to receive the word with Joy of the Holy Ghost, Two of His Fruits were made evident, Faith and Joy Gal 5:22
22 But the fruit of the Spirit is love, joy, peace, longsuffering, gentleness, goodness, faith,
lets add longsuffering as well, since Paul said they received it [the word] with much affliction !
The Apostle's Preached Faith and Repentance as commandments to every Born Again sinner to make evident their Sonship, their calling and Election, which they had a right to because they had been born of God Jn 1:12-13
12 But as many as received him, to them gave he power to become the sons of God, even to them that believe on his name:
13 Which were born, not of blood, nor of the will of the flesh, nor of the will of man, but of God.