Trevor Muirhead, aged 43, and Neil McKenzie, aged 42, are accused of plotting to kill Mr Lennon, former Scottish MP Trish Godman, lawyer Paul McBride, and various people in the premises of Cairde Na hÉireann in Glasgow by sending improvised explosive devices to them.
It is alleged the offence, which happened between March 1 and April 15, 2011, was aggravated by religious prejudice.
McKenzie, of Saltcoats, Ayrshire, and Muirhead, of Kilwinning, denied all charges against them when they appeared at Glasgow High Court yesterday.
The men are accused of sending Mr Lennon a package which they allegedly believed comprised an improvised explosive device, capable of igniting and exploding, causing severe injury and death to another person.
It is alleged that the package, sent to Mr Lennon at the Celtic FC training centre at Lennoxtown, held a plastic bottle containing the explosive substance tri-acetone tri-peroxide with a wire attached and a plastic bag containing a bag of nails and a watch component.
They are charged with sending similar devices to Ms Godman and Cairde Na hÉireann. It is alleged that the package sent to Mr McBride at Parliament House, Edinburgh, comprised a plastic bottle containing petrol, with wire attached, a plastic glove, nails and a watch component.
They are charged with sending the devices with the intention that the contents would ignite and explode when opened, causing severe injury and death to the recipients.
It is alleged that the pair bought nails, envelopes, travel bottles and digital sports watches at two shops in Stevenston, Ayrshire, and induced another man to buy cream peroxide.
The two men face an alternative charge that they conspired to cause an explosion “likely to endanger life or cause serious injury to property”.
They are accused of attempting to defeat the ends of justice by disposing of cream peroxide and wiring used to make improvised explosive devices.
A trial date was set for November 21.