For a good but simple summary of the origin and purpose of Lent, read:
https://stmatthewsnewport.com/wp-content/uploads/2019/03/LENT-Meaning-of.wpd-revised.pdf
In the church of my youth (my first 21 years), Lent was not observed. Later, when I became a United Methodist pastor, I came to view this oversight as a spiritual tragedy. It is one thing not to observe Lent; it is quite another to disparage those who do. That indeed is a sign of judgmental spiritual immaturity. My congregation learned to appreciate how sensitivity to the church calendar helped them identify and upgrade their spiritual journey.
The disrespect posters display towards Lenten observance mirrors their indifference to the life of the Christian as spiritual journey. It is far too easy to forget about Jesus' teaching on the need for continual confession of sin, repentance, and the need for self-denial for the prospective disciple. Lent begins with Ash Wednesday, a service devoted to renewed self-assessment and meditation on areas of hidden sin that need recognition, confession, and repentance. In many churches, these unconfessed sins are written down on a piece of paper to ensure that the penitent seeker is more serious about the cost of discipleship than the mockers on this site. Then this paper is publicly burnt to signify the marvelous truth that God buries their sins in the sea of His forgetfulness and then puts up a sign that says, "No fishing!" So when we continue to wallow in guilt feelings, after repentance, we are fishing in a No Fishing zone! Towards the end of the service, congregants come forward to allow the pastors to apply ash to their foreheads in the shape of a cross. In the OT, penitents combined fasting with an application of ashes to demonstrate the seriousness with which they take authentic repentance. When the congregation disperses to shop for food, etc,, this cross-shaped ash bears eloquent testimony to the basic requirements of true discipleship.
The 40 days of Lent extend from Ash Wednesday to Easter Sunday, but Sundays don't count in the calculation. The 40 day duration recalls Moses' 40 day fast in Mount Sinai, Elijah's 40 day fast on his journey to Mount Sinai (= Mount Horeb), and Jesus' 40 day fast during His time of testing in the wilderness at the beginning of His public ministry. So Lenten fasting is a way of imitating these spiritual giants and making self-denial real and not just a pious part of our spiritual self-image.
Besdies the themes of confession, repentance, and self-denial, Lent begins with an emphasis on spiritual testing during our spiritual journey. Lenten observers find this helpful because believers often lose sight of how regularly we are tested in our daily walk. Failure to notice these tests often means test failure! Lent also stresses the process of spiritual rebirth and transformation. On Palm/ Passion Sunday and even on preceding Sundays, Lenten services focus on Holy Week in Jesus' final days, so that the events leading up to His crucifixion are understood as a coherent whole. The service on Holy Thursday often includes either a Passover meal or a foot washing ceremony for meditation on the messianic symbolism of the Passover meal and the true meaning of Jesus' foot washing episode in John 13. On Good Friday, of course, the church altar is stripped to draw attention to the horror of Jesus' suffering on the cross in anticipation of the redecoration of the altar during the triumphant processional hymn (usually "Christ the Lord is Risen Today") on Easter Sunday. Lenten disciplines thus enhance the anticipation and joyful celebration on Easter Sunday.
