17th century Baptists on Gospel Offers

From the 1644 London Particular Baptist Confession of Faith  (SEE HERE)
(emphasis mine)
VI.

(1) This therefore is life eternal, to know the only true God, and whom He has sent Jesus Christ.(2) And on the contrary, the Lord will render vengeance in flaming fire to them that know not God, and obey not the Gospel of our Lord Jesus Christ.

1) John 17:3; Heb. 5:9; Jer. 23:5, 6
2) 2 Thes. 1:8; John 3:36

XXIV.

That faith is ordinarily(1) begot by the preaching of the Gospel, or word of Christ, without respect to(2) any power or capacity in the creature, but it is wholly(3)passive, being dead in sins and trespasses, does believe, and is converted by no less power,(4) then that which raised Christ from the dead.

1) Rom. 10:17; 1 Cor. 1:21
2) Rom. 9:16
3) Rom. 2:1, 2; Ezek. 16:6; Rom 3:12
4) Rom. 1:16; Eph. 1:19; Col 2:12

XXV.

That the tenders of the Gospel to the conversion of sinners,(1) is absolutely free, no way requiring, as absolutely necessary, any qualifications, preparations, terrors of the Law, or preceding ministry of the Law, but only and alone the naked soul, as a(2) sinner and ungodly to receive Christ, as Christ, as crucified, dead, and buried, and risen again, being made(3) a Prince and a Savior for such sinners.

1) John 3:14, 15; 1:12; Isa. 55:1; John 7:37
2) 1 Tim. 1:15; Rom. 4:5; 5:8
3) Acts 5:30-31; 2:36; 1 Cor. 1:22-24

From the 1689 London Particular Baptist Confession of Faith  (SEE HERE)

10. Effectual Calling

Those whom God has predestinated to life, He is pleased in His appointed and accepted time to effectually call by His Word and Spirit, out of that state of sin and death which they are in by nature, to grace and salvation by Jesus Christ...Man is dead in sins and trespasses until quickened and renewed by the Holy Spirit. By this he is enabled to answer the call, and to embrace the grace offered and conveyed by it. This enabling power is no less power than that which raised up Christ from the dead.

20. The Gospel and Its Influence

The covenant of works being broken by sin, and made unprofitable for life, God was pleased to promise Christ, the seed of the woman, as the means of calling the elect and bringing to life within them faith and repentance. In this promise the substance of the Gospel was revealed and shown to be the effectual for the conversion and salvation of sinners.

This promise of Christ and the salvation which comes by Him, is revealed only by the Word of God. The works of creation and providence with the light of nature do not reveal Christ or His grace even in a general or obscure way. How much less, therefore, can those who are devoid of the revelation of Christ by the promise (or the Gospel) be enabled by the light of nature to arrive at saving faith or repentance.