Ok, could you explain Paul's assertion in 1 Cor. that God was well pleased through the foolishness of the message preached to save those who believe?
Sure. First, understand that the Monergist believes in something called the effectual call. The 1689 Second London Baptist of Faith explains it this way:
10.1 Those whom God hath predestinated unto life, he is pleased in his appointed, and accepted time, effectually to call, by his Word and Spirit, out of that state of sin and death in which they are by nature, to grace and salvation by Jesus Christ; enlightening their minds spiritually and savingly to understand the things of God; taking away their heart of stone, and giving unto them a heart of flesh; renewing their wills, and by his almighty power determining them to that which is good, and effectually drawing them to Jesus Christ; yet so as they come most freely, being made willing by his grace.
Passages to consider are Rom. 8:30; Eph. 1:10; 2 Thes. 2:13-14; Eph. 2:1-6 et. al.
The verse you did not fully reference is 1 Cor. 1:21:
1 Corinthians 1:21 For since in the wisdom of God the world through its wisdom did not
come to know God, God was well-pleased through the foolishness of the message preached to save those who believe.
The Gospel is the means of salvation. God has ordained the preaching of the Gospel as the means (or method) of calling His elect. If you look closely at verses 18-19; 24; 27-28 you will see God's calling clearly revealed. Those that believe the foolishness of the message preached are those whom God has effectually called to eternal life.