As I said here: encourage people to develop social bonds to a community of secularists among whom altruist activities are highly valued, preferably one with mechanisms to prevent cheap methods for signaling altruism from displacing those activities.
I doubt religion per se has much to do with altruism. But religious communities are typically tangible and visible and persistent, and that's important for the transmission of values.
And, sure, encouraging people to perform acts that benefit others, even if they don't want to, is possible without dishonesty. Force is a popular alternative, for example... either physical or social. Whether that's a good thing or not is another question.
For example, many countries collect taxes from residents and use a significant share of those taxes to provide resources to citizens in need; many taxpayers don't especially value providing resources to their fellow citizens, but nevertheless pay taxes.
I'd quite forgotten about force.
I see a lot of activism that is carried out by groups which, if not specifically secularist, are not explicitly religious, but this tends to be single-issue stuff. Religious communities, in my experience, tend to teach on or examine or respond to every aspect of life (though it is debateable how successful most are, as there is nowadays the problem of people leaving if they don't like what they hear). Are there secular movements which attempt to be so all-embracing?
I've long entertained a dubious regard for the practice of lying to children about the existence of Santa Claus. Parents might claim that it serves to make children's lives more magical and exciting, but as a general rule, children are adequately equipped to create fantasies of their own without their parents' intervention. The two reasons I suspect rest at the bottom line are adherence to tradition, and finding it cute to see one's children believing ridiculous things.
Personally, I considered this to be a rather indecent way to treat one's own children, and have sometimes wondered whether a large proportion of conspiracy theorists owe their origins to the realization that practically all the adults in the country really are conspiring to deceive children for no tangible benefit. However, since I began frequenting this site, I've been exposed to the alternate viewpoint that this realization may be good for developing rationalists, because it provides children with the experience of discovering that they hold beliefs which are wrong and absurd, and that they must reject them.
So, how did the Santa deception affect you personally? How do you think your life might have been different without it? If your parents didn't do it to you, what are your impressions on the experience of not being lied to when most other children are?
Also, I promise to upvote anyone who links to an easy to register for community of conspiracy theorists where they would not be averse to being asked the same question.