Muslims say they do not worship idols. When they go to Mecca, why do they kiss a black stone?

Isn't that like worshippingan idol?
Muslims do not worship the black stone. They regard the stone as a
created thing. The most fundamental principle of Islam is that nothing
or no one is to be worshipped except Allah, the one true God.
Muslims who can afford the journey are required once in their lifetime
to visit the House of Worshipin Makkah. This was the first house built
for the worship of the one true God. It was constructed byAbraham and
his son Ishmael, peace be upon them. The black stone was brought to
them from heaven by the angel Gabriel to function as a corner stone.
It was thus affixed in one corner.
Because Muslims kiss that stone, some observers hastily conclude that
Muslims worship it. A kiss, however, is not an act of worship unless
it is accompanied by an intention to worship. If you kiss your child,
for instance, that does not mean you worship your child.
Some may find it strange that Muslims should treat a stone with
respect. But this is not just any old stone. It is an item out of
paradise.
The act of fixing a stone to mark a place of worship is as old as
history. In the Bible we are told that Jacob, on whom be peace, had
fixeda stone at a place where he saw a vision. He poured oil on it and
calledit Bethel meaning 'house of God' (see Genesis 28:18). He did
this again upon God's instruction (see Genesis 35:1, 14, 15). No one
should understand from this that God instructed Jacob to worship the
stone.