The Grace of God;The Bitter Root

Ephesians 2:
1 And you were dead in the trespasses and sins
2 in which you once walked, following the course of this world, following the prince of the power of the air, the spirit that is now at work in the sons of disobedience—
3 among whom we all once lived in the passions of our flesh, carrying out the desires of the body and the mind, and were by nature children of wrath, like the rest of mankind.
4 But God, being rich in mercy, because of the great love with which he loved us,
5 even when we were dead in our trespasses, made us alive together with Christ—by grace you have been saved—
:6 and raised us up with him and seated us with him in the heavenly places in Christ Jesus,
7 so that in the coming ages he might show the immeasurable riches of his grace in kindness toward us in Christ Jesus. 

Hebrews 2:
1 Therefore we must pay much closer attention to what we have heard, lest we drift away from it.
2 For since the message declared by angels proved to be reliable, and every transgression or disobedience received a just retribution,
3 how shall we escape if we neglect such a great salvation? It was declared at first by the Lord, and it was attested to us by those who heard,
4 while God also bore witness by signs and wonders and various miracles and by gifts of the Holy Spirit distributed according to his will. 

Hebrews12:15  See to it that no one fails to obtain the grace of God; that no "root of bitterness" springs up and causes trouble, and by it many become defiled;

It is evident that there are many who preach "the doctrines of grace" and still manage to heap a form of law and works, along with the outcome of such preaching; condemnation, upon the hearers whether regenerate or not. Christ came to save the sinners that the Father had given Him to save. Only the elect have been given ears to hear and eyes to see, (Proverbs 20:12; Matthew 13:13-16).
The assurance is that none of the elect will fail to believe the Gospel. All for whom he died are saved. When we forget the depth of the grace God has shown us, we end up looking foolish; and of course only in the most pious of manner.
So let us stick to His plan and cease trying to convince the unregenerate of God's truth, as only the Lord knows who will hear and believe on a day to day basis. We are not hear to make projects out of any to whom we present the Gospel, nor to make projects out of those who do hear and believe.

Acts 2:
42 And they devoted themselves to the apostles' teaching and the fellowship, to the breaking of bread and the prayers.
43 And awe came upon every soul, and many wonders and signs were being done through the apostles.
44 And all who believed were together and had all things in common.
45 And they were selling their possessions and belongings and distributing the proceeds to all, as any had need.
46 And day by day, attending the temple together and breaking bread in their homes, they received their food with glad and generous hearts,
47 praising God and having favor with all the people. And the Lord added to their number day by day those who were being saved.