After one has studied John, 1 John, and Mark, I would recommend that they move to the Gospel of Luke. As a gospel that was written to a Greek audience, Luke is obliged to write in such a way that Jewish customs and words are made more understandable, unlike Matthew, which was written to a Jewish audience. Therefore, one could be made more ready to understand Matthew if one studies the other gospels first. However, since Luke is longer than Mark, I recommend one to study Mark before Luke, since Mark has to give a more understandable and basic account of the life of the Lord Jesus Christ.
In Luke, the Lord Christ is portrayed as Jesus, the perfect human being, who is as much a part of history as any other person. In this gospel, we see the believer’s example of living, who is completely dependent upon the Father, and lives His life by the power of the Holy Spirit. In addition, we see the perfect example of obedience, who perfectly obeyed the Father to earn His favor for all believers, and then died to bear punishment from the Father in their place. Then, He rose from the dead as the last Adam, who has conquered death, and has ensured that all the dead will also rise.