First, while it is beyond reasonable doubt that God works out everything in conformity with the purpose of his will (Ephesians 1:11), that does not mean that he does not desire things that for wise and holy reasons he does not decree to bring about. For instance, God has not ordained to save all human beings even though he does not take pleasure in the death of the wicked but rather is pleased when their turn from their ways and live (Ezekiel 18:23 cf. 33:11). Similarly, God wants us to pray for everyone because he wants all people to be saved and to come to a knowledge of the truth (1 Timothy 2:1-4), and he patiently delays judgment not wanting anyone to perish, but everyone to come to repentance (2 Peter 3:9). Attempts to restrict "all" and "everyone" to the "elect" in these passages are misguided and fail to appreciate that there is a complexity to the divine mind and will that resists overly simplistic interpretations.
Second, with regard to the death of Christ on the cross, the longstanding theological summary "sufficient for all, efficient for the elect" is difficult to improve on. Considered, in itself, the death of the God-man is sufficient to remove the all sins of all the lost sons and daughters of Adam. There should be no hesitancy to affirm the intrinsic value and efficacy of the atonement of Jesus Christ, the ultimate high priest and sacrifice. There is no other hope for lost human beings no matter who they are. And there is no other sacrifice that can wash away the stain of human sin and satisfy all the demands of a just and holy God. Although there are other important things that need to be said about texts like John 3:16 and 1 John 2:1-2, when all has been said about the nuances of "world" and "whole world" in these verses, I think it is impossible to escape the truth that Jesus' death is sufficient for everyone the world over if they believe in him. Of course, this is not all that should be said. Jesus did not die to make salvation a mere hypothetical possibility. He came on a mission of mercy and he died to save his people from their sins (Matthew 1:21), and he will do exactly that (John 17:2).
Third, entry into the church, as a new covenant community, is by faith in Jesus Christ and is not on the basis of an election which has not been verified by the reality of personal faith and repentance. No one has any business assuming, or telling anyone else, that they are part of the eschatological community of God, the new Israel, the new humanity, etc. (to name just a few ways the church is described in the New Testament) if they have not called upon the name of the Lord Jesus (Roman 10:9-13). God's election is only known as sinners come to faith in Christ (1 Thessalonians 1:4-6; 2 Thessalonians 2:13-14). Any other suggestion, no matter how august its proponents, is unbiblical theological presumption that undermines the gospel, even though that may not be the intention. The purposes of God in election remain veiled and beyond the realm of human knowledge until they break into space and time in the spiritual rebirth of those who were dead in their sins until God makes them alive in Christ Jesus. As soon as this rebirth occurs, faith in Christ is the result.
It is tragic when the great truths of the gospel lay buried beneath the rubble of error. But it is equally tragic when their rediscovery is marred and obscured by a lack of balance. In this day we must guard against distortions of truth just as vigorously as we do ignorance of the truth. Both are dangerous. Biblical balance is essential and it is possible if we bring our ideas to the touchstone of God's word. As professor John Murray said years ago, "Truth is a razor's edge."