Beith's father was a land agent and farmer in the Kintyre district of Argyleshire, and was a man of wide reading, especially in theology and church history.

After the usual course of education at Campbeltown, young Beith entered the Glasgow University, on 20 November 1811, with a view to the ministry of the church of Scotland.

[10] Alexander Beith was married to Julia Robson, whom he had met in Oban when at the age of fifteen she became a communicant member of his congregation.

Those wanting a new chapel had stated in their petition, "the difference between the dialects of the West and North Highlands is so great that the natives of the one frequently do not understand at all the language spoken in the other."

Alexander Beith became the first minister of Hope Street Gaelic Chapel, and although his ministry was a short one, no doubt his Argyll dialect was acceptable to this new congregation.

He was presented in 1830, by Lord Glenelg, and Drysdale comments that, special circumstances in each case made it manifest that he should accept the appointments, although he doesn't give his source.

In the moving little book which Alexander Beith wrote about that sad period, Sorrowing yet Rejoicing,[12] he tells how the servants were then summoned.

I could then easily understand how other ministers were so ready to accept calls to go elsewhere; and I confess to you, what I never said in public before, that when proposals were made to me to be removed to Edinburgh, to one of the charges there, and made three times, the question of conscience at the time of the Disruption was not stronger with me than when I was called to decide whether I should go, and quit the state of things in Stirling, or stay and fight against it, and try, at least, to reform things.

[15] When the agitation on the subject of spiritual independence was reaching a crisis in the church of Scotland, Beith was one of the seven ministers appointed in 1842 to preach at Strathbogie in spite of the prohibition of the civil courts.

Now, however, his attention was directed to how matters would fare with his own congregation, and on his arrival from Edinburgh on the Saturday evening he found they had secured the Corn Exchange, where service was conducted for about a year when what was known as "the little church" was opened.

Beith regularly conducted two lengthy services every Sabbath, together with a week-day lecture, taking, besides, a prominent part, not only in Presbyterial and general ecclesiastical matters, but in public affairs as well, but, in 1869, following upon a severe illness, he was appointed an assistant.

When the deposition of William Robertson Smith was first moved in the assembly, Beith proposed and carried a motion that the charges be withdrawn and the professor be restored to his chair at Aberdeen University.

[7] Beith retired from the active service of the church in Stirling in 1876 but continued to take part in the general work of the denomination.

Towards the end of 1876 Dr Beith intimated his intention of retiring from the active duties of the pastorate, and on 26 April 1877, John Chalmers of Ladyloan Free Church, Arbroath, was inducted as colleague and successor.

Another son, John Alexander, was a justice of the peace and closely connected for many years with philanthropic and educational work in Manchester; he died in October 1896.

A portrait of Dr. Beith, painted by Norman MacBeth, was presented to him by his congregation in Stirling and passed into the possession of his son Gilbert in Glasgow.