What makes one a coward? Well, if you google the definition for coward you get this.
Now, what exactly do these so-called cowardly Calvinists not have the courage to do? Well, they don’t have the courage to “Call Arminianism Heresy.” Us Calvinists who aren’t willing to damn the majority of Arminians are said to be at odds with the Synod of Dort. Well, just what did the Synod of Dort say about Arminianism? We know they approved of the Council of Ephesus’ decision on Pelagianism, and we know that they often mentioned Pelagius’ name when discussing doctrinal distinctions.
Interestingly enough, the Synod never used Peter’s term ἀπώλεια αἵρεσις (apōleia hairesis or Damnable Heresy) They often just used the word heresy. This is an important point because what we could have here is a case of misreading your definition of a word into someone else’s. Now, I’m not going to sit here and tell you that the Synod of Dort was nice to the Arminians, they simply weren’t, they exiled them. What they didn’t do, however, is preach the gospel to them. If you notice something, as heated as a debate as it was, it still was what it was, an in-house debate. Sometimes you kick a family member out of your house, that doesn’t make them not family. Many at the Synod of Dort were more against Pelagianism, and because Arminianism is a step towards that direction from a Calvinist point of view, they rightly were pointing out that this train could stop at the other side of Ephesus. Also, if anyone uses 2 Peter 2:1 in reference to an Arminian, kindly point out the context of 2 Peter, where Peter is talking about those who “deny the Lord that bought them.”
The Synod of Dort
But hey, why believe a guy on the internet about the Synod of Dort, right? Well, would you believe William Ames?(Adviser to the Synod of Dort)
Finally it should be noted that Ames did not call down the usual orthodox vituperation on his opponents. In the Conscience he asks if the Remonstrants are heretics and gives this answer:
‘The position of the Remonstrants, as held by most that favor it, is not properly a heresy but a dangerous error in the faith, tending to heresy.’
He goes on to say, however, that when the Remonstrant view on the role of the will is pushed too far, it does become a heresy– ‘a Pelagian heresy, because it denies the effectual operation of internal grace to be necessary for the effecting of conversion and faith.’ Here the line must be drawn” (pp. 7-8). 
If this cowardly Calvinist thing is true, there were quite a few cowardly Calvinists in history.
Some “Cowardly” Calvinists
Like Charles Spurgeon who said
The controversy which has been carried on between the Calvinist and the Arminian is exceedingly important, but it does not so involve the vital point of personal godliness as to make eternal life depend upon our holding either system of theology. Between the Protestant and the Papist there is a controversy of such a character, that he who is saved on the one side by faith in Jesus, dares not agree that his opponent on the opposite side can be saved while depending on his own works. There the controversy is for life or death, because it hinges mainly upon the Doctrine of Justification by Faith, which Luther so properly called the test Doctrine, by which a Church either stands or falls. The controversy, again, between the Believer in Christ and the Socinian, is one which affects a vital point. If the Socinian is right, we are most frightfully in error; we are, in fact, idolaters, and how can eternal life dwell in us? And if we are right, our largest charity will not permit us to imagine that a man can enter Heaven who does not believe the real Divinity of the Lord Jesus Christ. There are other controversies which thus cut at the very core, and touch the very essence of the whole subject.
I think we are all free to admit, that while John Wesley, for instance, in modern times zealously defended Arminianism, and on the other hand, George Whitefield with equal fervor fought for Calvinism, we should not be prepared, either of us, on either side of the question, to deny the vital godliness of either the one or the other. We cannot shut our eyes to what we believe to be the gross mistakes of our opponents, and should think ourselves unworthy of the name of honest men if we could admit that they are right in all things, and ourselves right, too! … We are willing to admit—in fact we dare not do otherwise—that opinion upon this controversy does not determine the future or even the present state of any man!
Or the thundering Evangelist, George Whitfield who when asked if they’d see John Wesley in Heaven replied
“I fear not, for he will be so near the eternal throne and we at such a distance, we shall hardly get sight of him.”
 Reforming America Ministries FB Page (In particular, their recent posts.)
 Conscience: Its Law or Cases, Five Books, IV, iv, 10.
 Exposition of the Doctrines of Grace no. 385
Wycliffe Handbook of Preaching and Preachers, W. Wiersbe, Moody Press, 1984, p. 255
 Peterson and Williams, Why I Am Not an Arminian (IVP, 2004), pp. 10-14.
 Calvin’s commentaries (Grand Rapids, 1964) pg 387-388.