Moderate Calvinists—who regard the doctrines of sovereign grace as “just points” of theology that should never divide anyone and not essentials of the Gospel—have nothing substantial to offer to the discussion about Arminianism. If moderates cannot see that Arminianism and the doctrines of grace are polar opposites that are diametrically opposed, they do not have a biblical understanding of the true Gospel. And if moderates affirm Arminians as their brothers in Christ, despite the fact that there are no Arminian Bible verses, they need to repent for their ignorance.
If the above describes you, it is possible that you don't understand the Gospel yourself and can't really discern between the true Gospel and the counterfeit which opposes it.
The difference between the true Gospel of the Reformation and the false gospel of Arminianism is not merely a difference between theological systems or secondary doctrines.
The sad reality is that it is impossible to affirm universal atonement and the absurd notion of contra-causal freedom [viz. free-will] as Arminians do, and simultaneously believe in the imputed righteousness of Christ alone for justification. Arminians affirm a false gospel because they perpetuate the lie that Jesus only made salvation, redemption, and reconciliation a possibility for all who will meet a condition, while the biblical Gospel teaches that Christ procured the Father’s favor, and He saved, redeemed, and reconciled all of the elect for whom He died.
Arminians worship a different christ. Universal atonement and libertarian freedom are two beloved Arminian doctrines that are not found anywhere in Scripture. Christ died for His sheep, not the goats. And the Bible teaches that “salvation is of the Lord,” not salvation is of the Lord because some poor sinner exercised their frail and depraved will to either accept or deny Christ who died for all without exception. The Bible explicitly says that Christ actually saved His particular people, while Arminians insist that Jesus only made men savable.
Arminians believe in a different god. The Arminian god did not ordain his elect to be saved or condemned, but had to look into the future to learn what “free-will” decisions his creatures will make. This god is not omniscient. In fact, this god is no god at all! The God of the Bible is all powerful and all knowing, who elects His chosen objects of love to be saved, and His vessels of wrath to be condemned.
Arminians also have a blasphemous definition of grace. They affirm prevenient grace, which is universally applied to all men, to include the reprobate. And they believe that God’s grace can be resisted. But the Bible teaches that God’s grace is discriminative, effectual, and irresistible.
To remain faithful to Christ, local church pastors must draw a dividing line between the true Gospel of Jesus Christ and the false gospel of semi-pelagianism, or they will be judged one day as hirelings that sowed tares among the wheat. Faithful elders will protect the flock of God from the lies of Arminianism, while hirelings will sweep it under the rug as simply a division between mature and immature brethren.
If you meet an Arminian, do not anathematize them. Witness to them and do not refer to them as brothers in Christ. If you do, you are misleading them to believe that they affirm the same Gospel as you do. Instead, love them by declaring the true Gospel to them. The Gospel is mighty to save! And we believe that God can save them. True love warns. Maranatha.