Maitland did not stay long at Norwich, and was admitted to priest's orders by Henry Ryder, Bishop of Gloucester.
Bishop | bishop | Gloucester | Bishop (Catholic Church) | Bishop of Winchester | Bishop of London | titular bishop | Bishop of Durham | Bishop of Ely | Titular Bishop | Prince Richard, Duke of Gloucester | Metropolitan bishop | Bishop of Lincoln | Bishop of Chester | Bishop Auckland | Bishop of Exeter | Robert, 1st Earl of Gloucester | Bishop of Rochester | Bishop of Llandaff | Titular bishop | The Case of the Stuttering Bishop | Gloucester Cathedral | Earl of Gloucester | Bishop of Meath | Bishop of Bath and Wells | Stephen Bishop | Duke of Gloucester | metropolitan bishop | Elizabeth Bishop | Bishop's Stortford |
He made rapid progress in the Church, and was made successively prebend of Westminster in 1607; Rector of West Isley, Berkshire, in 1616; Rector of Kinnerton, Gloucester; Canon of Windsor in 1617; Dean of Rochester in 1621; and finally Bishop of Gloucester, 1624-1655.
Though he took part in the trial of John Hooper, Bishop of Gloucester, and served also on a commission to try Nicholas Ridley and Hugh Latimer, in general he took no active part in the proceedings on the score of heresy.
To Robert Frampton, the nonjuring bishop of Gloucester, Firmin remarked, ‘I hope you will not be a nonconformist in your old age.’ Frampton retorted that Firmin himself was ‘a nonconformist to all Christendom besides a few lowsy sectarys in Poland.’ On the Protestant exodus from Ireland in 1688–9 Firmin was the principal commissioner for the relief of the refugees; more than £56,000 went through his hands, and eight of the Protestant hierarchy of Ireland addressed to him a joint letter of thanks.