I know it was quite common for Catholics to use force & trickery in converting people in the past. What about protestants?
Since you asked, the very founders of Protestantism themselves authorize torture and murder.
ENGLAND
King Henry erected a system built on fear, torture and death to back his attack on the Catholic Church. Criticising the king, calling him a heretic, or failing to agree that Henry was head of the church, were punished by **disembowelment whilst still alive, hanging and quartering. **In the end, even failing to denounce anyone else who criticised these things became treason. Guilty verdicts were ensured by the introduction of the “Double Grand Jury” which made the jury trying a case liable to face trial themselves by a second jury if they came up with the wrong verdict. Acts of Attainder, allowing the execution of victims without any trial whatsoever, were also introduced. All these things were needed to enforce the Reformation in England.
Abbots who refused to surrender their monasteries also fell victim: Letter of Richard Pollard to Thomas Cromwell, November 16, 1539
Pleaseth it your Lordship to be advertised that…[On November 15] the late abbot of Glastonbury went from Wells to Glastonbury, and there was drawn through the town upon a hurdle to the hill called the Torre, where he was put to execution; …Afore his execution [he] was examined upon divers articles and interrogatories to him ministered by me, but he could accuse no man of himself of any offence against the king’s highness, nor would he confess no more gold nor silver nor any other thing more than he did before your Lordship in the Tower…I suppose it will be near Christmas before I shall have surveyed the lands at Glastonbury, and take the audit there….
On 8 April, 1538, Friar Forrest was taken to Lambeth, where, before Cranmer, he was required to state that King Henry was Head of the Church. This, however, he firmly refused to do. Forrest was sentenced to death, and on the 22nd of May he was taken to Smithfield and burned. To add to the “godly” humour of this public spectacle, the friar was burnt over a bonfire of religious statuary.
After Catholics rose up in protest at the closing of the Monasteries in 1536, King Henry wrote: Our pleasure is that . . . you shall cause such dreadful execution to be done upon a good number of the inhabitants of every town, village, and hamlet that have offended, as they may be a fearful spectacle to all others hereafter that would practice any like matter. Hundreds were massacred at random in the Catholic areas.
Others
disembowelled or burnt within months included:1534: Elizabeth Barton, q.v. (The Holy Maid of Kent), with five companions;John Dering, O.S.B., Edward Bocking, O.S.B., Hugh Rich, O.S.F., Richard Masters p., Henry Gold p., 1537. Monks, 28. - After the pilgrimage of grace and the rising of Lincolnshire many, probably several hundred, were executed, of whom no record remains. The following names, which do survive, are grouped under their respective abbeys or priories. - Barling: Matthew Mackerel, abbot and Bishop of Chalcedon, Ord. Præm. Bardney: John Tenent, William Cole, John Francis, William Cowper, Richard Laynton, Hugh Londale, monks. Bridlington: William Wood, Prior. Fountains: William Thyrsk, O. Cist. Guisborough: James Cockerel, Prior.Jervaulx: Adam Sedbar, Abbot; George Asleby, monk. Kirkstead: Richard Harrison, Abbott, Richard Wade, William Swale, Henry Jenkinson, monks. Lenten: Nicholas Heath, Prior; William Gylham, monk. Sawlet: William Trafford, Abbott; Richard Eastgate, monk. Whalley: John Paslew, Abbott; John Eastgate, William Haydock, monks. Woburn: Robert Hobbes, Abbott; Ralph Barnes, sub-prior; Laurence Blonham, monk. York: John Pickering, O.S.D., Prior. Place unknown: George ab Alba Rose, O.S.A. Priests: William Burraby, Thomas Kendale, John Henmarsh, James Mallet, John Pickering, Thomas Redforth. Lords: Darcy and Hussey. Knights: Francis Bigod, Stephen Hammerton, Thomas Percy. Laymen (11): Robert Aske, Robert Constable, Bernard Fletcher, George Hudswell, Robert Lecche, Roger Neeve, George Lomley, Thomas Moyne, Robert Sotheby, Nicholas Tempest, Philip Trotter. 1538 (7): Henry Courtney, the Marquess of Exeter; Henry Pole, Lord Montague; Sir Edward Nevell and Sir Nicholas Carew; George Croft p., and John Collins p.; Hugh Holland l… Their cause was “adhering to the Pope, and his Legate, Cardinal Pole”. 1540 (6): Lawrence Cook O. Carm., Prior of Doncaster; Thomas Empson, O.S.B.; Robert Bird p.; William Peterson p.; William Richardson p.; Giles Heron l. 1544 (3): Martin de Courdres, O.S.A., and Paul of St. William, O.S.A.; Darby Genning
Over the next few reigns around 600 Catholic priests alone, and thousands of ordinary Catholics were disembowelled or otherwise murdered by Protestants because of their faith. Topcliffe, Elizabeth’s chief torturer, had a special house full of torture equipment to be used on Catholic priests. One elderly priest was tortured 12 separate times to gain information on other priests and believers.
CALVIN
Within a few years of Calvin coming to power in Geneva fifty-eight sentences of death and seventy-six of exile took place. Two examples:
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