A Templar should be Christian since Knight Templar is he who is a member of the Catholic Church. This is because they have to act in the order of the church and they have to make sure that they really do their duties as Christians. It is like they are sacristan holding swords and responsible for some blood. This is their duty.
This is why a Templar must be:
Faithful to the Church. He should have this initiative to make sure that that he will not go against any regulation of the church established for Knights.
Fearless and Bold. These are very important to those who are holding swords since they have to to for a fight for some reasons. So they always have to devote their a time pf prayer to ask for protection. If they will die, it is honor and glory to them.
They must possess Chivalry. Chivalry is choosing what is right from wrong even though there are temptations at times. It is very natural for all people to choose the desire of their hearts but for knights, they have to carry on gentleness and upright decision. If they fall in love, they must learn how to control their emotions and fulfill their duty first. This is chivalry.
Strong heart. In unpleasant situations and unfavorable circumstances, they must be strong enough to hold on and to carry on their mission and overcome hardships that they will have to go through all their life. Longing for home is a basic reaction of the body but they have to suppress their emotions.